If the onset of a light reliably signals the onset of food, a rat in a Skinner box will work to turn on the light. In this case, the light is a reinforcer.

well we can't tell you because we cant see the time give a screen shot or something.

it is a learned trait

explanation:

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.