How can geologists tell what order Rrick layers formed I. ? A new Rick layers from on top of existing Rock layers b new rock layers from on bottom of existing rock layers c top rock layers are older or d top rock form first

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.