Read the following sentence from the passage.
It began to move more quickly, stirring the heavy air.
Which answer choice correctly identifies the two adverbs in the sentence and the words they modify?
A. "began" modifies "it"; "more" modifies "move"
B. "more" modifies "move"; "quickly" modifies "move"
C. "more" modifies "quickly"; "quickly" modifies "move"
D. "quickly" modifies "move"; "heavy" modifies "air"