Which sentence uses a verb that agrees with its subject? A. The new volunteers at the fire station are waiting for their first call. B. Four players on the team is out because of injuries. C. In the afternoon, the traffic on the highways grow. D. The leaves on our tree is not green any more.

Sentence A has a verb which agrees because:

In sentence B, the four players are plural so the 'is' should be 'are'

In sentence C, the traffic implies pluralisation so the traffic on the highways 'grows'

In sentence D, the 's' on the end of the word leaves make the leaves plural and so the 'is' should be 'are'