A valley with steep, parallel walls along the faultlines, formed by the subsidence of a part of earth's crust is known as ________

Answer: Option D

A valley with steep, parallel walls along the faultlines, formed by the subsidence of a part of earth's crust is known as Rift Valley. A rift valley is a lowland region that forms where Earth's tectonic plates move apart, or rift. Rift valleys are found both on land and at the bottom of the ocean, where they are created by the process of seafloor spreading.