Which sentence is NOT a simple sentence?

AShe enjoys golf but prefers swimming.
BThe cat in our backyard screeched horribly all night.
CThe entire property is surrounded by a chain-link fence.
DBoth my friend and I left our bicycles at the recreation center.

Verified Answer :

A simple sentence contains the basic element that make a sentence and
that is a subject and a predicate. The sentence must one independent clause and
expresses one idea.

In the choices enumerated above

 a. She enjoys golf but prefers
swimming

is not a simple sentence because it does not represent one ide but two.
If you break down the sentence, it could be:

‘She enjoys golf’ and ‘She prefers swimming’.

The rest of the choices contain one idea only.