This doesn’t mention deep meaning, so it can’t be right. We’re looking for an answer that links the conclusion (folktales are deeply meaningful) with the premise (folktales provide insight into a culture’s wisdom). (A) is only concerned with concepts contained in the premise!

(B) links the concept of insight into a culture’s wisdom (from the premise) with the idea of deep meaning (from the conclusion). If folktales provide insight into the wisdom of a culture, and anything that does so is deeply meaningful, then folktales are deeply meaningful!

The literary critic’s argument is that folktales possess deep meaning, so this statement about tales that lack deep meaning is irrelevant.

(D) reverses the sufficient and necessary conditions of the statement we’re looking for: (D) says any deeply meaningful tale provides great insight. We want to know that any tale that provides great insight is deeply meaningful.

We know folktales are told in an entertaining way, but not that they’re told primarily for entertainment. So (E) describes a type of story that folktales might not be in! Also, we want to show that folktales are deeply meaningful, not that they don’t necessarily lack deep meaning.