Answer:
A) Divergent currents push up part of the plates. Then gravity pulls on those areas, bringing them downward. And, as these areas move lower, the ridges then push the plates away and outward.
Step-by-step explanation:
The movement of plate tectonics is governed by two forces namely the ridge push and gravitational force. When the hot magma rises due to ridge rush on the spreading sea floor it creates higher elevation when it cools and solidifies.
The divergent movement causes new solidified magma back to the subduction zone due to the gravitational pull. The downward pull of plate motion is prompted by the weight of the older and dense plate material which sinks back at the ocean trenches causing slab pull.