9.

Answer and Explanation

Your Answer is

Correct Answer is A

Explanation

This question examines the modification of different constituents by adverbs and prepositional phrases.

Item C/D: carefully adverb modifies check so it cannot be separated from check with a comma.

Item B: prior to "before...", prior to printing prepositional phrases, modify the entire sentence in front, and place it at the beginning or end of the sentence.