Which sentence is in “passive voice”?

Choose the best answer from the options below:
A Cereal was served by the cafeteria staff at breakfast.
B Henry ate the leftover pizza in the refrigerator.
C The other driver blamed the accident on me.
D Each of the contestants won a gift.

A Cereal was served by the cafeteria staff at breakfast.

The sentence in passive voice is: A) Cereal was served by the cafeteria staff at breakfast.

In this sentence, the subject (Cereal) is being acted upon (served), rather than performing the action itself.