Weathering, Erosion, Deposition Summary about it

Weathering is the breakdown of rocks at the Earth's surface, by the action of rainwater, extremes of temperature, and biological activity. It does not involve the removal of rock material.

Erosion is the process by which the surface of the Earth gets worn down. Erosion can be caused by natural elements such as wind and glacial ice. ... The key to erosion is something called "fluid flow." Water, air, and even ice are fluids because they tend to flow from one place to another due to the force of gravity.

Deposition is the geological process in which sediments, soil and rocks are added to a landform or landmass.

i'm thinking (a) to keep sand in place; ////////////

explanation: a sand fence or sandbreak, like a snow fence, is used to force windblown, drifting sand to accumulate in a desired place. sand fences are employed to control erosion, sand dune stabilization, keep sand off roadways, and to recruit new material in desert areas.