Answer:
C.
They irrigated dry land to expand their farmlands.
D.
They used oxen-drawn plows and seed funnels to plant crops more quickly and easily.
Explanation:
Sumerians developed irrigation techniques to benefit from the Tigris and Euphrates floods. Through canals, they would flood the fields even after the flood season, and then drain the water. They would also use oxen to trample the ground and kill weeds. After that, they would work intensely on the field before planting the seeds.
