(A) says that to understand one topic (major trends in research on aging), one must understand that topic’s effects (the influences of these trends on society’s view).

Instead of understanding the effects of a topic, the stimulus says one must understand the earlier subjects that influenced the original subject of study.

While (B) discusses how understanding earlier events enables full understanding of the historical events of this century, it is missing the aspect of “significant influence” specified in the stimulus. (B) just mentions that the historian must study “similar events in earlier centuries;” there is no indication that these similar events were significantly influential on the contemporary events that the historian is studying.

(C) says that to understand one subject (French), one must understand subjects that share roots with that subject (the other languages with common linguistic ancestry).

Instead of understanding similar topics with shared origins, the stimulus says one must understand the earlier subjects that influenced the original subject of study.

(D) says that in order to understand any subject, one must understand the broader practices related to that topic. This is different from the stimulus, which says that one must understand the earlier subjects that influenced the original subject of study.

This example about the influence of Plato on Aristotle’s philosophy illustrates that scholars’ understanding of a subject is enhanced by studying the earlier subjects that influenced that subject.