5. The type of climax vegetation that becomes established in an area depends most upon the
(1) rate of photosynthesis in autotrophs (3) climatic conditions present
(2) number of carnivores present (4) concentration of nitrogen in the air

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.

i need