The many volcanoes located along the edge of the pacific ocean make up the ring of fire. how does subduction play a role in the volcanic activity in the ring of fire?
a)most of the plate boundaries involve one plate sliding underneath another.
b)most of the plate boundaries involve plates spreading apart, forming new ocean floor.
c)most of the plates are stationary, capable only of forming hot spots.
d)most of the plates rub horizontally against each other.

A. Most of the plate boundaries involve one plate sliding underneath another.

Along the Ring of Fire, subduction causes one plate to slide beneath another. The bottom plate plunges into the mantle. Once in the mantle, the plate melts and can then rise up as a volcano.

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.