A IS CUT PART OF STEM WHICH IS PLACED ON A STOCK (ANOTHER ROOTED STEM) 1.GRAFT
2.SCION
3.LAYER
4.CUT

Explanation:

SCION is the answer.

Hope it helped you.

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.