Choose the correct description of the conveyor-like action of plate tectonics on earth
a - earth's mantle is broken up into plates that float beneath the overlying lithosphere. the bottoms of the mantle's convection cells drag the tops of the plates, making them move. this movement causes spreading in some places and subduction in others.
b - earth's lithosphere is broken up into plates that float beneath the overlying mantle. the bottoms of the mantle's convection cells drag the tops of the plates, making them move. this movement causes spreading in some places and subduction in others.
c - earth's lithosphere is broken up into plates that float on the underlying mantle. the tops of the mantle's convection cells drag the bottoms of the plates, making them move. this movement causes spreading in some places and subduction in others.
d - earth's mantle is broken up into plates that float on the underlying lithosphere. the tops of the mantle's convection cells drag the bottoms of the plates, making them move. this movement causes spreading in some places and subduction in others.