Answer: D. to inform readers of the reasons why the Grimms more often be artificial collected their tales.
Step-by-step explanation: In the given excerpt from "How the Grimm Brothers Saved the Fairy Tale" we can see the description of the reasons why the Grimm Brothers concentrated on old German epics, tales and literature instead of concentrating in modern literature, that is because they thought modern literature was artificial and old literature was the most natural and pure form of culture. So the purpose of the text is to inform the reader about those reasons.