Answer:
C. Tectonic plates.
Step-by-step explanation:
The series given in the question is mantle...convection...volcano...cooling...crust..motion and then tectonic plate is next.
here the process started in mantle where hot lava was moving and due to convection, this molten lava came on the the surface in the form of volcano and cooled down and rocky crust was formed and the moving crust is known as tectonic plates.