Which choice demonstrates passive voice? a) the waiter apologized to the angry customer. b) a delivery truck just pulled up to the dock. c) the chipped glass was replaced with a new one. d) every day, mechanics check planes before they depart.

C)The chipped glass was replaced with a new one.

The easiest way for me to identify passive voice is to look at the subject and verb of the sentence. Passive voice happens when the subject is receiving the verbs action rather than doing it. For example, in option A the subject is the waiter and the verb is apologized. The waiter is the one doing the apologizing so this is NOT passive voice. However, in option C, glass is the subject and replaced is your action verb. The glass can't do the replacing. The glass is receiving the action of being replaced. This means it is written in passive voice.