In which sentence is the word barn used as the OBJECT OF A PREPOSITION?

A. The Sutters' barn and fence need a new coat of paint.
B. The barn owl flies silently through the night.
C. John found the dog asleep in the barn.
D. Close the barn door when you leave

A. The Sutters' barn and fence need a new coat of paint.

The sentence in which the word "barn" is used as the object of a preposition is:

C. John found the dog asleep in the barn.