Answer:
b
Explanation:
its b because it doesnt say any else then 15 or any clues so its tryna trick u
I'm not sure what you mean by "compartments", but the cardiovascular system consists of the heart, blood vessels, and approximately 5 liters of blood.
Electrons have a negative charge so when a element looses its electrons it will have a positive charge
To oxygenate your blood cells.