Which best describes how ocean ridges form?

a - pressure from lava being pushed up from the earth adds new material to the ocean floor, creating a ridge.

b - the flat action of the water shears off the top of a seamount, creating a ridge.

c - decaying materials filter from above, creating ridges.

d - corals grow on a submerged rim, forming circular ridges above the water.

A - Pressure from lava being pushed up from Earth adds the new material to ocean floor, creating ridge.

They form due to the convection currents at the divergent boundary that causes the rise of magma. The ridge rush and the slab pull processes are responsible for the formation of an ocean ridge.  

Ridge push causes the uplifting and spreading of the tectonics away from the ridges and directs them towards the subduction zone. At the zone of the subduction, slab-pull causes the old plate material down onto the subduction zone or in the earth's mantle. At the ridge, the constant rising and cooling of the mantle create a high elevation.