Psychologists observing a shopping mall parking lot found that, on average, drivers spent 39 seconds leaving a parking space when another car was quietly waiting to enter it, 51 seconds if the driver of the waiting car honked impatiently, but only 32 seconds leaving a space when no one was waiting. This suggests that drivers feel possessive of their parking spaces even when leaving them, and that this possessiveness increases in reaction to indications that another driver wants the space.

Which one of the following, if true, most weakens the reasoning?

Shark teeth are among the most common vertebrate fossils; yet fossilized shark skeletons are much less common—indeed, comparatively rare among fossilized vertebrate skeletons.

Which one of the following, if true, most helps to resolve the apparent paradox described above?

Geologists recently discovered marks that closely resemble worm tracks in a piece of sandstone. These marks were made more than half a billion years earlier than the earliest known traces of multicellular animal life. Therefore, the marks are probably the traces of geological processes rather than of worms.

Which one of the following, if true, most weakens the argument?

Often a type of organ or body structure is the only physically feasible means of accomplishing a given task, so it should be unsurprising if, like eyes or wings, that a type of organ or body structure evolves at different times in a number of completely unrelated species. After all, whatever the difference of heritage and habitat, as organisms animals have fundamentally similar needs and so _______.

Which one of the following most logically completes the last sentence of the passage?

Engineer: Thermo-photovoltaic generators are devices that convert heat into electricity. The process of manufacturing steel produces huge amounts of heat that currently go to waste. So if steel-manufacturing plants could feed the heat they produce into thermo-photovoltaic generators, they would greatly reduce their electric bills, thereby saving money.

Which one of the following is an assumption on which the engineer’s argument depends?

Archaeologist: After the last ice age, groups of paleo-humans left Siberia and crossed the Bering land bridge, which no longer exists, into North America. Archaeologists have discovered in Siberia a cache of Clovis points—the distinctive stone spear points made by paleo-humans. This shows that, contrary to previous belief, the Clovis point was not invented in North America.

Which one of the following, if true, would most strengthen the archaeologist’s argument?

Librarian: Some argue that the preservation grant we received should be used to restore our original copy of our town’s charter, since if the charter is not restored, it will soon deteriorate beyond repair. But this document, although sentimentally important, has no scholarly value. Copies are readily available. Since we are a research library and not a museum, the money would be better spent preserving documents that have significant scholarly value.

The claim that the town’s charter, if not restored, will soon deteriorate beyond repair plays which one of the following roles in the librarian’s argument?

When people show signs of having a heart attack an electrocardiograph (EKG) is often used to diagnose their condition. In a study, a computer program for EKG diagnosis of heart attacks was pitted against a very experienced, highly skilled cardiologist. The program correctly diagnosed a significantly higher proportion of the cases that were later confirmed to be heart attacks than did the cardiologist. Interpreting EKG data, therefore, should be left to computer programs.

Which one of the following, if true, most weakens the argument?

Psychiatrist: In treating first-year students at this university, I have noticed that those reporting the highest levels of spending on recreation score at about the same level on standard screening instruments for anxiety and depression as those reporting the lowest levels of spending on recreation. This suggests that the first-year students with high levels of spending on recreation could reduce that spending without increasing their anxiety or depression.

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

A recent poll revealed that most students at our university prefer that the university, which is searching for a new president, hire someone who has extensive experience as a university president. However, in the very same poll, the person most students chose from among a list of leading candidates as the one they would most like to see hired was someone who has never served as a university president.

Which one of the following, if true, most helps to account for the apparent discrepancy in the students’ preferences?

Quasars – celestial objects so far away that their light takes at least 500 million years to reach Earth – have been seen since 1963. For anything that far away to appear from Earth the way quasars do, it would have to burn steadily at a rate that produces more light than 90 billion suns would produce. But nothing that burns at a rate that produces that much light could exist for more than about 100 million years.

If the statements above are true, which one of the following must also be true on the basis of them?

The odds of winning any major lottery jackpot are extremely slight. However, the very few people who do win major jackpots receive a great deal of attention from the media. Thus, since most people come to have at least some awareness of events that receive extensive media coverage, it is likely that many people greatly overestimate the odds of their winning a major jackpot.

Which one of the following is an assumption on which the argument depends?