Which sentence contains a verb in the passive voice?

AThe dude ranch is located in the Grand Teton National Park.
BOne day we saw a moose and an elk off in the distance.
CFrom camp, we had a spectacular view of Grand Teton Mountain.
DA bear was heard snorting near our camp last night.

Verified Answer :

The correct answer should be D. A bear was heard snorting near our camp last night.

In order for it to be active you would say "We heard a bear snort near our camp last night". Was + heard is used to create a passive construction. Other sentences are in active voice.