Answer:
The correct option is C. Nadamos en la piscina.
Step-by-step explanation:
To swim (nadar/nadamos), you need water and a space to do it (pool, sea, ocean, etc.). Then, you cannot swim in a ship, since it is a large, sail or motor boat that can have a deck as well (such as a boat, a sailboat, a yacht, etc.). Then the correct term to use the word "ship" would be "navigate"
I hope my explanation has served you. luck!