The placement of the quote also seems important. The quote comes right after we get these subtle hints of the author's opinion. It seems that Fruton was used to emphasize the author's subtle point or, if we don't really know if the author really feels so strongly about competition, Fruton was used to emphasize the main point of the article.
- (A) seems great!
(B) First of all, Fruton's quote is more abstract and less concerned with cytology and biochemistry in specific. In addition, there really isn't any "new evidence" being presented. We would have little reason to believe that the LSAT would give us a brand new piece of information and leave us with a cliffhanger
(C) No way! The biochemists are long gone! We are dealing with the abstract here!
(D) Nah. Fruton is emphasizing the GOOD encountered when two disciplines compete. Also, Fruton is not really talking about "synthesis" of disciplines. In fact, he is talking about when disciplines are polarizing.
(E) Like (C), this is just flat out wrong.
(A) is clearly the best answer and, if we didn't know the Author's opinion before, we certainly do now!