Yall pls im failing pls dont comment just for points help me if u dont know the answer dont comment

Objects that are more dense, or have more mass, travel at a slower rate than less dense objects, and will need more force applied to make it go faster. A golf ball and a ping-pong ball may be the same size, but, a golf ball has more mass than the ping-pong ball does, so the golf ball has a greater density. Meaning that the golf ball will travel slower than the ping pong ball because the same amount of force was applied to both.

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.