What has played the most important role in shaping the physical landscape of east africa?

Tectonic processes has played most important role in shaping the physical landscape of east Africa.

Explanation:

A rift valley is a swamp area that appears where Earth's tectonic plates shift apart or rift. Rift valleys occur both on land and about the depths from the ocean, where all are formed by the process of seafloor expanding. Tectonic plates are tremendous, rocky parts of Earth's lithosphere-its outside and above the mantle.