Read "The Players." What was most likely the author's purpose?
Abel
to inform
to educate
to entertain
to persuade

the answer to your question is b

these muscles maintain the blood pressure in the vessels. the smooth muscles are innervated by nerves of the autonomic nervous system. when the muscles contract, they cause vasoconstriction of the vessels and increase blood pressure. when the muscles relax, they enable vasodilation of the   blood vessels hence reduce blood pressure.