Describe the discovery of the cell. Mention Robert Hooke and Anton van leeuwenhoek in the answer

d. planting trees

the trees take in carbon to make oxygen.

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.