the tropical sahel region is particularly vulnerable to drought, but its ecosystems have mechanisms to cope and recover from this stress. what terms describes the ability of sahel regions to cope through drought cycles?

Although the tropical Sahel region is especially susceptible to drought, it has RESILIENCE (the ability to cope through drought cycles). This implies that its ecosystems possess mechanisms to not only cope through, but also to recover from the stress of drought.

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.