How can scientists produce beneficial traits in organisms

genetic engineering

Explanation:

it's anything that aren't producers and consumers.

explanation:

you've got to be clear on what "this" is

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.