DNA is the ultimate control of cell's productions. So A.
Answer:
They sleep on just one side of their brain at a time
Explanation:
Dolphins are different from fishes that can breathe underwater.
It is necessary for them to get to the surface of the water at intervals to breathe air.
While sleeping, dolphins allows one hemisphere of their brains fall asleep while the other half is fully conscious. This means that If the left brain is sleeping, the right eye stays open and if the right brain is sleeping, the left eye stays open.
This happens so they always know when it's time to surface and breathe and when to escape when there is trouble.
The answer is A is you agree no problem im here to help if you disagree its ok i tried my best to help just saying