On steep slopes and mountains, reduce erosion by creating level areas for crops.

D. Terracing

Explanation:

Terracing is a type of landscaping characteristic for steep slopes and mountains. Graduated terraces are used to farm on this kind of terrain to reduce erosion. This way crops are planted on graduated level areas and not on steep terrain, and risk of surface runoff is reduced.

parasites can detrimentally affect their host, but also must not allow their host to die before they can complete their life cycle. some parasites have complex life cycles with many different hosts, and have had to find ways of persisting in many different environments during the change from one host to another. ectoparasites live outside the body of the host, and can more easily  disperse, but are  more exposed to predators, parasites, parasitoids. endoparasites live inside the body of the host, and are therefore protected from the outside environment. but they can be  attacked by the host's immune system. they have therefore developed  mechanisms for dispersal such as  complex life cycles.

i think it’s c but i might be wrong. if i am let me know! have a good rest of your day as well!