Good question! For this one, you really want to focus on how aggressive the author is being with his or her tone, without being afraid to call it like it is. There are a number of examples in this passage of a disagreeing tone being taken by the author. Let’s pinpoint some examples to help bring this answer choice into context.
Lines 1 through line 8 start off telling us Darwin himself didn’t like to reduce his theory, but the strict constructionists did just that. Being the creator of the theory, Darwin is being used as an appeal to authority that speaks against the viewpoint of the constructionists.
Line 16, “If the strict constructionists are right...†down to line 22, taking special note of line 19 where it says “But in fact...†is a good example of where the author is directly contradicting the strict constructionist point of view. The following paragraphs (paragraph 3 and paragraph 4) both serve to elaborate on the author’s position, directly countering the views of the strict constructionists and providing further evidence for the author’s stance in this point of disagreement.
Because the author is blatantly trying to refute the claims of the strict constructionists, we get to A) emphatic disagreement.
Answer choice B, mild disapproval, is too weak. The author spends most of the passage refuting the strict constructionist viewpoint, so “mild disapproval†doesn’t accurately characterize the tone of the author, which is much more antagonistic.