In some cases, cells are made and sent back to the bone marrow.

c: warm water flows from the western tropical pacific toward south america. that should be the right answer! hope it .

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.