So since this is a principle example question, the principle that I extracted from the argument was something along the lines of: "in order to understand a certain thing that is more recent, you should have a clear understanding of certain things that influenced the recent thing." So basically the key is about understanding something's influence on something else which would lead to a better understanding.
Would (C) be wrong because just "sharing linguistic ancestry" doesn't tell us whether those shared ones had an influence on the French language per se?
But a question I had with (E) was whether we had to assume that someone being someone's intellectual mentor necessarily means that the former influenced the latter. All I got from (E) was that Plato was Aristotle's intellectual mentor -- but I had to make an assumption myself which was that because Plato is Aristotle's intellectual mentor, Aristotle's philosophy was heavily influenced by Plato's.. but couldn't it be possible that although Plato was Aristotle's intellectual mentor, their philosophy could be completely different -- Aristotle may not agree with Plato's philosophy.. right? Does anyone see my point?