In the human body, the circulatory systems are made up of smooth muscle.
Option (a);
Step-by-step explanation:
The circulatory system of a body helps to transfer nutrients and oxygen from the small intestine and the lungs respectively to the cells of the body.
This reduces the waste content from the human body.
The blood vessels of the circulatory system are made up of smooth muscle tissue.
The smooth muscle cells around the blood vessels help to regulate the blood flow to the different segments of the body.
It helps to change the diameter of the arteries.
When the arteries constrict, it reduces the space for blood to flow increasing the blood pressure.