Which sentence contains an infinitive or infinitive phrase?

A.
Dangling from the branch was a perfect apple.

B.
This mountain is difficult to climb even for a frequent hiker.

C.
Will you send this small package to Uncle Mike?

D.
Yes, the phone had rung once this afternoon.

Please do NOT answer if you aren't 100% sure. I'm behind in school and I have to get this right.