Why Is Understanding the Hydrologic Cycle Important to Understanding How

Why is understanding the hydrologic cycle important to understanding how landscapes form?

A) because water has the ability to seep underground and affect the layers of rock
B) because the oceans cover a vast majority of our planet and are a main erosional agent
C) because the rate at which groundwater moves through the subsurface determines erosion rates
D) because water is the main agent of erosion and deposition on the Earth