For nearly a century, physiologists erroneously believed that a buildu

OFFICIAL EXPLANATION

The question asks us to analyze the structure of the argument. Specifically, it asks us to determine the relationship of the two bolded sentences to the argument as a whole. To do this effectively, we need first to determine the conclusion of the argument. In this case, the conclusion is the final sentence, which follows from the evidence presented in the rest of the argument. So we know that the correct answer cannot describe either bolded portion as the author's final conclusion.

The first bolded portion is presented as an earlier, erroneous belief. In evaluating the answer choices, we should look to eliminate any that suggest the author agrees with this first statement. The second bolded statement shows that the earlier theory (that lactic acid causes soreness) was incorrect, and thus also provides evidence in support of the author's conclusion. So we know that the correct answer must describe the second bolded portion as supporting the conclusion. The correct answer must describe both portions correctly, not just one or the other.

(A) This choice misrepresents the first bolded portion by claiming that the author accepts it as true, when the author actually presents it as an incorrect, outdated belief. The second portion is also incorrect because it indicates that the second bolded portion supports the first one.

(B) This choice also misrepresents the first portion, for the reason described above. It corrects the second bolded portion, however, by describing it as contradictory to the first portion.

(C) The first portion is correctly described as an assertion that the author does not believe to be true. Yet the second portion is incorrectly described as going against the author's final conclusion.

(D) CORRECT. This choice correctly represents the first portion by saying the author believes it is no longer valid. The second portion is correctly described as evidence in support of the author's conclusion.

(E) The first portion is correctly described as evidence considered by the author to be invalid. However, this choice misrepresents the second portion as the conclusion, when it is actually evidence given in support of the conclusion.