Advertisement: At most jewelry stores, the person assessing the diamond is the person selling it so you can see why an assessor might say that a diamond is of higher quality than it really is. But because all diamonds sold at Gem World are certified in writing, you’re assured of a fair price when purchasing a diamond from Gem World.
The reasoning in the advertisement would be most strengthened if which one of the following were true?
a) Many jewelry stores other than Gem World also provide written certification of the quality of their diamonds.

b) The certifications of diamonds at Gem World are written by people with years of experience in appraising gems.

c) The diamonds sold at Gem World are generally of higher quality than those sold at other jewelry stores.

d) The diamond market is so volatile that prices of the most expensive diamonds can change by hundreds of dollars from one day to the next.

e) The written certifications of diamonds at Gem World are provided by an independent company of gem specialists.

Statistician: A financial magazine claimed that its survey of its subscribers showed that North Americans are more concerned about their personal finances than about politics. One question was: "Which do you think about more: politics or the joy of earning money?" This question is clearly biased. Also, the readers of the magazine are a self-selecting sample. Thus, there is reason to be skeptical about the conclusion drawn in the magazine’s survey.

Each of the following, if true, would strengthen the statistician’s argument EXCEPT:

(A) The credibility of the magazine has been called into question on a number of occasions.
(B) The conclusions drawn in most magazine surveys have eventually been disproved.
(C) Other surveys suggest that North Americans are just as concerned about politics as they are about finances.
(D) There is reason to be skeptical about the results of surveys that are biased and unrepresentative.
(E) Other surveys suggest that North Americans are concerned not only with politics and finances, but also with social issues.
(A) The credibility of the magazine has been called into question on a number of occasions.

(B) The conclusions drawn in most magazine surveys have eventually been disproved.

(C) Other surveys suggest that North Americans are just as concerned about politics as they are aboutfinances.

(D) There is reason to be skeptical about the results of surveys that are biased and unrepresentative.

(E) Other surveys suggest that North Americans are concerned not only with politics and finances, but also with social issues.

Modern navigation systems, which are found in most of today’s commercial aircraft, are made with low-power circuitry, which is more susceptible to interference than the vacuum-tube circuitry found in older planes. During landing, navigation systems receive radio signals from the airport to guide the plane to the runway. Recently, one plane with low-power circuitry veered off course during landing, its dials dimming, when a passenger turned on a laptop computer. Clearly, modern aircraft navigation systems are being put at risk by the electronic devices that passengers carry on board, such as cassette players and laptop computers.

Which one of the following, if true, LEAST strengthens the argument above?

(A) After the laptop computer was turned off, the plane regained course and its navigation instruments and dials returned to normal.

(B) When in use all electronic devices emit electromagnetic radiation, which is known to interfere with circuitry.

(C) No problems with navigational equipment or instrument dials have been reported on flights with no passenger-owned electronic devices on board.

(D) Significant electromagnetic radiation from portable electronic devices can travel up to eight meters, and some passenger seats on modern aircraft are located within four meters of the navigation systems.

(E) Planes were first equipped with low-power circuitry at about the same time portable electronic devices became popular.
(A) After the laptop computer was turned off, the plane regained course and its navigation instruments and dials returned to normal.

(B) When in use all electronic devices emit electromagnetic radiation, which is known to interfere with circuitry.

(C) No problems with navigational equipment or instrument dials have been reported on flights with no passenger-owned electronic devices on board.

(D) Significant electromagnetic radiation from portable electronic devices can travel up to eight meters, and some passenger seats on modern aircraft are located within four meters of the navigation systems.

(E) Planes were first equipped with low-power circuitry at about the same time portable electronic devices became popular.

Amphibian populations are declining in numbers worldwide. Not coincidentally, the earth’s ozone layer has been continuously depleted throughout the last 50 years. Atmospheric ozone blocks UV-B, a type of ultraviolet radiation that is continuously produced by the sun, and which can damage genes. Because amphibians lack hair, hide, or feathers to shield them, they are particularly vulnerable to UV-B radiation. In addition, their gelatinous eggs lack the protection of leathery or hard shells. Thus, the primary cause of the declining amphibian population is the depletion of the ozone layer.

Each of the following, if true, would strengthen the argument EXCEPT:
(A) Of the various types of radiation blocked by atmospheric ozone, UV-B is the only type that can damage genes.
(B) Amphibian populations are declining far more rapidly than are the populations of nonamphibian species whose tissues and eggs have more natural protection from
UV-B.
(C) Atmospheric ozone has been significantly depleted above all the areas of the world in which amphibian populations are declining.
(D) The natural habitat of amphibians has not become smaller over the past century.
(E) Amphibian populations have declined continuously for the last 50 years.

(A) Of the various types of radiation blocked by atmospheric ozone, UV-B is the only type that can damage genes.

(B) Amphibian populations are declining far more rapidly than are the populations of nonamphibian species whose tissues and eggs have more natural protection from
UV-B.

(C) Atmospheric ozone has been significantly depleted above all the areas of the world in which amphibian populations are declining.

(D) The natural habitat of amphibians has not become smaller over the past century.

(E) Amphibian populations have declined continuously for the last 50 years.

According to the theory of continental drift, in prehistoric times, many of today’s separate continents were part of a single huge landmass. As the plates on which this landmass rested began to move, the mass broke apart, and ocean water filled the newly created chasms. It is hypothesized, for example, that South America was once joined on its east coast with what is now the west coast of Africa.

Which one of the following discoveries, if it were made, would most support the above hypothesis about South America and Africa?

(A) A large band of ancient rock of a rare type along the east coast of South America is of the same type as a band on the west coast of Africa.

(B) Many people today living in Brazil are genetically quite similar to many western Africans.

(C) The climates of western Africa and of the east coast of South America resemble each other.

(D) Some of the oldest tribes of people living in eastern South America speak languages linguistically similar to various languages spoken by certain western African peoples.

(E) Several species of plants found in western Africa closely resemble plants growing in South America.
(A) A large band of ancient rock of a rare type along the east coast of South America is of the same type as a band on the west coast of Africa.

(B) Many people today living in Brazil are genetically quite similar to many western Africans.

(C) The climates of western Africa and of the east coast of South America resemble each other.

(D) Some of the oldest tribes of people living in eastern South America speak languages linguistically similar to various languages spoken by certain western African peoples.

(E) Several species of plants found in western Africa closely resemble plants growing in South America.

Medical doctor: Sleep deprivation is the cause of many social ills, ranging from irritability to potentially dangerous instances of impaired decision making. Most people today suffer from sleep deprivation to some degree. Therefore we should restructure the workday to allow people flexibility in scheduling their work hours. Which one of the following, if true, would most strengthen the medical doctor’s argument?

a) The primary cause of sleep deprivation is overwork.
b) Employees would get more sleep if they had greater latitude in scheduling their work hours.
c) Individuals vary widely in the amount of sleep they require.
d) More people would suffer from sleep deprivation today than did in the past if the average number of hours worked per week had not decreased.
e) The extent of one’s sleep deprivation is proportional to the length of one’s workday.

a) The primary cause of sleep deprivation is overwork.

b) Employees would get more sleep if they had greater latitude in scheduling their work hours.

c) Individuals vary widely in the amount of sleep they require.

d) More people would suffer from sleep deprivation today than did in the past if the average number of hours worked per week had not decreased.

e) The extent of one’s sleep deprivation is proportional to the length of one’s workday.

Toxicologist: A survey of oil-refinery workers who work with MBTE, an ingredient currently used in some smog-reducing gasoline, found an alarming incidence of complaints about headaches, fatigue, and shortness of breath. Since gasoline containing MBTE will soon be widely used, we can expect an increased incidence of headaches, fatigue, and shortness of breath.

Each of the following, if true, strengthens the toxicologist’s argument EXCEPT:

(A) Most oil-refinery workers who do not work with MBTE do not have serious health problems involving headaches, fatigue, and shortness of breath.
(B) Headaches, fatigue, and shortness of breath are among the symptoms of several medical conditions that are potentially serious threats to public health.
(C) Since the time when gasoline containing MBTE was first introduced in a few metropolitan areas, those areas reported an increase in the number of complaints about headaches, fatigue, and shortness of breath.
(D) Regions in which only gasoline containing MBTE is used have a much greater incidence of headaches, fatigue, and shortness of breath than do similar regions in which only MBTE-free gasoline is used.
(E) The oil-refinery workers surveyed were carefully selected to be representative of the broader population in their medical histories prior to exposure to MBTE, as well as in other relevant respects
(A) Most oil-refinery workers who do not work with MBTE do not have serious health problems involving headaches, fatigue, and shortness of breath.

(B) Headaches, fatigue, and shortness of breath are among the symptoms of several medical conditions that are potentially serious threats to public health.

(C) Since the time when gasoline containing MBTE was first introduced in a few metropolitan areas, those areas reported an increase in the number of complaints about headaches, fatigue, and shortness of breath.

(D) Regions in which only gasoline containing MBTE is used have a much greater incidence of headaches, fatigue, and shortness of breath than do similar regions in which only MBTE-free gasoline is used.

(E) The oil-refinery workers surveyed were carefully selected to be representative of the broader population in their medical histories prior to exposure to MBTE, as well as in other relevant respects

Galanin is a protein found in the brain. In an experiment, rats that consistently chose to eat fatty foods when offered a choice between lean and fatty foods were found to have significantly higher concentrations of galanin in their brains than did rats that consistently chose lean over fatty foods. These facts strongly support the conclusion that galanin causes rats to crave fatty foods.

Which one of the following, if true, most supports the argument?
(A) The craving for fatty foods does not invariably result in a rat's choosing those foods over lean foods.
(B) The brains of the rats that consistently chose to eat fatty foods did not contain significantly more fat than did the brains of rats that consistently chose lean foods.
(C) The chemical components of galanin are present in both fatty foods and lean foods.
(D) The rats that preferred fatty foods had the higher concentrations of galanin in their brains before they were offered fatty foods.
(E) Rats that metabolize fat less efficiently than do other rats develop high concentrations of galanin in their brains.
(A) The craving for fatty foods does not invariably result in a rat's choosing those foods over lean foods.

(B) The brains of the rats that consistently chose to eat fatty foods did not contain significantly more fat than did the brains of rats that consistently chose lean foods.

(C) The chemical components of galanin are present in both fatty foods and lean foods.

(D) The rats that preferred fatty foods had the higher concentrations of galanin in their brains before they were offered fatty foods.

(E) Rats that metabolize fat less efficiently than do other rats develop high concentrations of galanin in their brains.