Which THREE sentences have the correct use of possessives?

Sandra’s life jacket was too tight, so she exchanged it for mine.

Most on the campground had pitched his tent already.

Neither Nick nor Jack had worn his helmet correctly.

“Them rocks,” said the guide “can be dangerous because of it’s jagged edges.”

Officer James’ post was not too far away.

Rafting on the Cossatot Rivers’ rapids is so exciting.

We wondered if the rafts would turn over on its side.