Bunuel
A recent university study indicated that students who receive full scholarships tend to maintain higher grade point averages than do students who must take out loans or work to finance school. The study concluded that scholarships enable students to achieve high grade point averages by alleviating the stress related to financial concerns and freeing up students' time to study more.
The study's conclusion depends on which of the following assumptions?
(A) Students who take out loans maintain higher grade point averages than those who work to finance school.
(B) Finance-related stress affects student performance in a manner similar to that of restricted study time.
(C) Students who must work to pay for their studies cannot maintain high grade point averages.
(D) High grade point averages were not the primary criterion upon which the scholarship awards were based.
(E) Controlling stress level is less important to student performance than is intensive studying.
KAPLAN OFFICIAL EXPLANATION:
Here's another study to ponder. The evidence of the study indicates that students on full scholarships maintain higher grade point averages (GPAs) than do students who work or take out loans. From this evidence, the study concluded that the scholarships "enable" those students to earn higher GPAs by alleviating financial stress and freeing up the students' time. Notice how the evidence links scholarships and higher GPAs, but the conclusion jumps into the realm of cause and effect—a common GMAT shift in scope. The word enable is your clue that the author is now speaking of a causal mechanism.
An 800 test taker understands the many ways that causation is suggested in GMAT arguments.
The author assumes that the only possible reason for the association is the causal mechanism cited in the conclusion, and the correct answer will very likely bolster this notion by eliminating an alternative explanation. Choice (D) hits on the right issue, and it should remind you of Nietzsche's Cornaro example presented earlier. It's possible that the author of this argument got the causal mechanism backwards. She argues that scholarships lead to high GPA's, but maybe the opposite is true: high GPA's lead to scholarships. The argument won't work if there's another reason for the correlation cited in the evidence. If high GPAs are the primary criterion for the scholarships in the first place, then it's not surprising that scholarship holders tend to earn higher GPAs than others. The students must generally be of otherwise equal ability before the conclusion can safely be drawn. (D) is the answer because it eliminates a very plausible alternative explanation for the correlation cited in the first sentence, and thus is the assumption on which this conclusion depends.
(A) offers an irrelevant comparison that does not make the study's conclusion any more likely. Even if students who take out loans do not maintain higher GPAs than those who work to finance school, students with scholarships can still maintain higher GPAs than both of the other groups.
(B) is irrelevant to the argument because it makes a comparison between the positive effects of scholarships. The argument concludes that more time and less financial worry together enable students to maintain higher GPAs. The conclusion does not rely on any particular distinction between these factors.
(C) is in no way required by the argument. Even if students who must work to pay for their studies can maintain high GPAs, the GPAs of scholarship students can still be higher.
(E), like choice (B), makes an irrelevant comparison. Stress and study time are two factors that may influence student performance, but there's no specific comparison of their relative importance that's necessary for this argument to work. Scholarships may still confer an advantage in the manner cited no matter what the relative importance of these factors may be.