Which sentence should be rewritten to use the active voice?

A. I cut the neighbor's grass so that I could afford to buy a ticket to the movies.

B. The pie was served carefully by Li, who gave the first slice to her grandmother.

C. My parents surprised me by bringing home a kitten on my last day of school.

D. Sandra walked her neighbor's dog while the neighbor was on crutches.

B. is correct.​