The theory of plate tectonics explains the movement of the plates by convection cells in which of the following layers
a. outer layer
b. upper mantle
c. inner core
d. crust

The correct answer is - B. upper mantle.

The theory of the plate tectonics uses the convection cells in the upper mantle layer as the foundation for the movement of the continents.

To put it simple the process is explained like the convection cells create a lot of pressure, that pressure, supported by the high temperatures and magma, influence the crust above, and manage to crack it on certain places. As the crust cracks, it becomes a separate entity, and under the enormous force from bellow it slowly moves into a particular direction, and that is actually the movement of the tectonic plates.