Psychologists have claimed that many people are more susceptible to

The stimulus begins by outlining the psychologists' argument, and quickly concludes that their argument is not well justified. This argument/counterargument structure is one of the most common and predictable paradigms in Logical Reasoning.

The psychologists claim that seasonal affective disorder is a real phenomenon, and as evidence point to surveys in which people were asked to recall how they felt at various times in the past. The author counters their argument by disputing whether people can accurately report on their past psychological states. If they can't, then the survey results don't justify the psychologists' position. This line of reasoning is logically sound: if the survey results aren't reliable, this would indeed weaken - though not disprove - the psychologists' argument. The stem asks us to describe the author's method of reasoning.

Answer choice (A) is incorrect, because no alternative explanation of the variation in the occurrence of psychological problems across seasons is provided.

Answer choice (B) is incorrect, because the author does not dispute whether SAD can properly be labeled as a "disorder."

Answer choice (C) is attractive, but incorrect. The representativeness of the population sample is never under debate. Rather, the problem is whether they can recall past psychological states. For answer choice (C) to be correct, the author should have observed that perhaps the surveys were conducted among patients suffering for PTSD, or among people being treated for depression. Here, the author points to a response bias, which influenced the response of participants away from a truthful response. This is different from the selection bias described in answer choice (C).

Answer choice (D) is the correct answer choice. Whenever we attack an opponent's position, our counterargument can be described as one that questions our opponent's assumption(s). Every counterargument does that. Here, we question the psychologists' assumption that people can accurately recall past psychological states. If they can't, then the psychologists' argument is immediately weakened. Thus, this is an assumption upon which their argument erroneously depends.

Answer choice (E) is incorrect, because the number of people affected by SAD is not under debate.

Psychologists have claimed that many people are more susceptible to psychological problems in the winter than in the summer; the psychologists call this condition seasonal affective disorder. Their claim is based on the results of surveys in which people were asked to recall how they felt at various times in the past. However, it is not clear that people are able to report accurately on their past psychological states. Therefore, these survey results do not justify the psychologist's claim that there is any such condition as seasonal affective disorder.

The author criticizes the psychologists claim by

(A) offering an alternative explanation of the variation in the occurrence of psychological problems across seasons - WRONG. Nothing like that. No explanation given.

(B) questioning whether any seasonal variation in the occurrence of psychological problems could properly be labeled a disorder - WRONG. Problem that affect this choice are disorder is bigger pool as compared to SAD.

(C) questioning the representativeness of the population sample surveyed by the psychologists - WRONG. Beyond scope. Rather its about accuracy that is questioned.

(D) questioning an assumption that the author attributes to the psychologists - CORRECT. POE helps. Dumbfounded myself this one said assumption that author suggests psychologists made and over that questioning it. But how smoothly psychologists made it is questionable and thus there has to be some assumption whihc helps them make such a conclusion.

(E) demonstrating that fewer people actually suffer from seasonal affective disorder than psychologists had previously thought - WRONG. Number of people suffering or suffered is out of question.

B and D are contenders for me but D wins with a slight advantage.

Answer D.