Answer:
The correct answer is the last option.
Explanation:
The bottlenose dolphins breathe air, however, at the same time can sleep in the ocean as it alternates with half of its brain as asleep and half as awake. This is due to the fact that half of the awake brain of a dolphin does not just keep the dolphin breathing, it also maintains the functioning of one eyeball so that it can see what is going in the surroundings, and at the same time, other eyeball remains shut.