Answer: D. All of the above
Step-by-step explanation:
Farmers in both the steppe and desert regions use irrigation to water their crops. They sometimes build canals to divert water from water bodies for irrigation.
Agriculture is very difficult in both areas as soils are poor. Famers therefore have to plant more drought resistant crops like palm trees.
Another economic activity in both areas is that of the nomadic herders who move herds of livestock around to feed for example the Fulani people of West Africa.