Answer:
The asthenosphere layer
Step-by-step explanation:
The asthenosphere is the layer that forms a portion of the upper part of the mantle and is present below the lithosphere. The rocks in this region are solid but they tends to flow during deformation. They behave in a plastic manner. The convection current generates in the mantle and the plates are forced to move over this viscous layer. This plate motion is because of the heat energy radiated from the core of the earth.