This is simply a logical conclusion of the question.

The word “because” is crucial here. BECAUSE a crystal has many facets, that is aspects, it stands to reason that the writer should offer “many facets” of ideas as well.

Actually, essays are more interesting if the writer picks one point of view and stays with it. If the “many facets” of ideas are mentioned, many of those ideas should be countered so that the reader is left with the dominant opinion of one point of view. Simply laying before the reader a bunch of ideas without organizing them behind a point of view is confusing and boring.

Therefore: answer this question with B.

But when it comes to YOU and how you will organize an interesting essay, pick C.