Concept:A rift valley is a long, narrow depression formed when the Earth's crust is pulled apart and blocks of land drop down between faults.
Explanation:Rift valleys are created by strong tensional forces in the Earth's crust.
These forces cause the crust to crack along parallel fractures.
The central block of land sinks downward between the fractures.
This process of cracking, sliding, and displacement along fractures is known as faulting.
Erosion and weathering only wear down existing landforms, not create rift valleys.
Folding bends rock layers but does not produce the sinking block structure of a rift valley.
Therefore, faulting is the correct process.
Answer:D. Faulting