What is one benefit of experimental investigations? O They do not have to be repeated.
O They show cause-and-effect relationships.
O They do not require data gathering.
O They are always realistic and identical to natural settings.

B

Explanation: They show cause-and-effect relationship.

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.  

answer; cnidarians;