Answer:
Option (C)
Step-by-step explanation:
The asthenosphere layer covers a small portion of the upper mantle and lies below the layer of lithosphere. This layer is very hot and viscous, due to the presence of extremely high pressure and temperature, as a result of which the rocks tends to flow slowly during the time of deformation. During the time of plate collision, the subducting plate reaches this layer and eventually melts and mixes with the magma. This layer is important because it helps in the movement of tectonic plates due to the formation of convection current in the mantle.
Thus, the correct answer is option (C).