Question 1 should be A, Because the blood inside the arteries is being pushed round by the heart, the blood pushes against the insides of the artery walls. This pushing is your blood pressure. To cope with this pressure, the artery walls contain tiny muscles to hold them in shape and allow them to become wider or narrower.
Question 2 should be D, because the cardiovascular system is made up of the heart, which pumps blood through the veins.
