Multi-choice problem: Continue writing the next sentence in this paragraph:

Several people are swimming in the pool. They are wearing caps on their heads. A life guard looks on. there

Choices:
[a]. is a shot put behind a net.;
[b]. is a boat pulling a boat behind him.;
[c]. is a net set up.;
[d]. is a dog that runs around in the pool.;
[c].