D. Purpose or the reason for which something is done or created or for which something exists.
It would be D. All of these . Each one if a form of natural disaster and severe weather.
Answer:
C. They provide details that create mental pictures for the reader.
Explanation:
Descriptions describe a person, place, or thing to help the reader better understand it.
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.