Currents inside earth might drive plate motion.
a. vertical
c. horizontal
b. convection
d. none of the above

B) Convection

The reason is because as the hot inner magma begins to rise (like normal hot air) and then sinks when it cools. This circular movement of magma causes the plates to move either apart from each other, together (and under/over) or against (rubbing)

Answerscripps institution of oceanography; i believe this is correct plz check first good luck;