Question

What is the driving force for the movement of the lithospheric plates?

Answer 1

For much of the last quarter century, the leading theory of the driving force behind tectonic plate motions envisaged large scale convection currents in the upper mantle, which can be transmitted through the asthenosphere.

Answer 2

as mentioned in ur earlier Q on constructive forces, the driving force for plates movement is from the heat energy from the Earth core.