Answer:
Option (D)
Step-by-step explanation:
The East African Rift valley is one of the best examples of the divergent plate motion. Here, the Somalian and the Nubian plate is moving in the opposite direction at a rate of about 5-7 mm every year. This rift started to form since the Oligocene Epoch. The formation of a rift valley is the starting of the continental separation and it eventually leads to the formation of seas.
This rift valley is currently an active rift, where the convection current is forcing the plates to move apart. The mantle plumes beneath this region are forcing the lithosphere to rise up and weakens it by stretching and breaking further by creating faults in its nearby places. In addition to this, volcanism also occurs adjacent to this type of plate motion.
These rift valleys are formed due to the tensional stress (force) that allows the plate to move in the opposite direction.
Hence, the correct answer is option (D).