Step-by-step explanation:
Plate tectonics is a theory derived from the theory of sea floor spreading and continental drift.
The theory proposes that the outer layer of the earth is broken down into series of slabs that moves over the mantle.
This outer layer of the earth is called the lithosphere. The lithosphere is made up of the crust and the upper mantle.
The layer below the lithosphere which allows for the movement of the lithosphere is called the asthenosphere.