Concept:Rift valleys are formed by parallel faulting when a block of crust sinks between two parallel faults.
Explanation:Tensional forces stretch the Earth's crust and create parallel fractures.
The block between these fractures slips downward along the fault planes.
This down-dropped block forms a linear depression known as a rift valley.
This is called parallel faulting, common at divergent plate boundaries.
The East African Rift Valley is a classic example.
Other landforms like inselbergs, dykes, and gorges have different origins.
Answer:D. Rift valley