Answer:
C. They irrigated dry land to expand their farmlands.
Step-by-step explanation:
The Sumerians were the earliest civilization known that was located in Mesopotamia. To increase food production the Sumerians had to create a system to irrigate the soil so they did not need to depend on natural rain for their water supply. To do so, the Sumerians excavated canals along the water courses and dug smaller feeder channels.