It is a modifying phrase considering of a preposition and it's object a noun out a pronoun. Hope this helps.
Answer: a. simile
Explanation:
Since the sentence uses the word "as" to compare, and similes contain the words "like" or "as," the sentence is a simile.
I would say that the answer is -
To put together a better outline for the essay.
Since it would help you put together your rough draft.
Hope i helped!
;D
One hundred years of solitude