Answer: (C) Plate movement
Step-by-step explanation:
The plate movement is one of the major cause of the great rift valley as the geologists realize that rift valley was basically framed by the fierce underground powers that destroyed the world's outside layer.
These powers made enormous pieces of the outside layer sink between the parallel separation points and power up the liquid shake in volcanic emissions.
The great Rift Valley is mainly framed by a unique plate limit, where the Amur plate is gradually tearing away and it has been doing as such for around 25 million years.
Therefore, Option (C) is correct.