Anthropologist: All music is based on a few main systems of scale building. Clearly, if the popularity of a musical scale were a result of social conditioning, we would expect, given the diversity of social systems, a diverse mixture of diatonic and non-diatonic scales in the world’s music. Yet diatonic scales have always dominated the music of most of the world.
Therefore, the popularity of diatonic music can be attributed only to innate dispositions of the human mind.The anthropologist’s argument is most vulnerable to criticism on the grounds that it fails to
(A) consider the possibility that
some people appreciate non-diatonic music more than they do diatonic music - WRONG. Exceptions does not help here. Also, the answer we are looking for is about why diatonic is popular.
(B) explain how innate dispositions
increase appreciation of non-diatonic music - WORNG. Rings wrong bells. Irrelevant.
(C) explain the existence of diatonic scales as well as the existence of non-diatonic scales - WRONG. Even if had explained it would had no impact on the passage.
(D) consider that innate dispositions and social conditioning could jointly affect the popularity of a type of music - CORRECT. While POE helps but it also helps us know that there might other possibilities behind popularity of diatonic music.
(E) consider whether any appreciation of
non-diatonic music is demonstrated by some nonhuman species of animals - WRONG. Altogether irrelevant.
Answer D.