Blood vessels are constructed of smooth muscle, which is capable of constricting, and slowing down. The correct option is a.
Blood vessels are the thin muscular tubes present in the whole body. There are two types of blood vessels. They are arteries and veins. Both have different functions.
The blood vessels carry the blood and regulate it into the entire body. The artery carries oxygenated blood to the body, and veins carry deoxygenated blood to the heart from the body.
Blood vessels are muscular and they are flexible. They can constrict and expand according to the blood flow. They also control the pressure of the blood. The walls of the arteries and veins are thin and at the same time strong to control the pressure of the blood.
Thus, the correct option is a. slow down.
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