I believe the answer is: B. To show that Grendel cannot rely on nature for protection
In the story, Grendel perceive that he is blessed by protection from the nature which would always help him in all of his troubles. But when he somehow got his foot stucked in a tree in front of a bull and when he cried and scream for help from the nature, he did not receive any answer.
I believe this would be True.
Expository essays explain. This could mean explaining Aristotle's relationship with Plato
It suggest something violent or dangerous