I believe it is this.
Part A
Imagination is a powerful force of creativity
Part B
Dickinson compares the “roof” of poetry to the limitless sky.
The answer is B because it doesn't have any commas and it wouldn't make sense without it. Looks like you got it correct.
Answer:
I think A tell me if I am right
Answer:
I belive it is Cassie
Explanation:
Because it describes her.