1. Why the circulatory system is more complex than the heart?
A because the circulatory comprises the other parts which helps to circulates blood to our body.
B. because the circulatory system is made up of blood vessels that carry blood away from and
towards the heart.
C. because the circulatory system carries oxygen, nutrients, and hormones to cells, and removes
waste products, like carbon dioxide.
D. all of the above.​