Answer:
The correct answer is C. Quietly is an adverb modifying closed.
Explanation:
The correct answer is C because the adverb quietly modifies the verb "closed" by telling the reader how the curtain was closed.
We know that option A is not correct because heavy does not describe velvet, it describes the curtain.
We also know that option B is not correct because quietly does not modify curtain, it modifies the verb closed.
Therefore, the answer is C.
Hope this helps!
