How did flooding rivers contribute to the beginning of farming communities?

AThey irrigated the crops when they overflowed.
BThey created a marshy environment good for planting.
CThey provided water and stayed within their banks.
DThey left rich soil when floodwaters receded.

Verified Answer :

DThey left rich soil when floodwaters receded.

they left rich soil when flood waters receded. So the correct option for the given question is option "d". It has been seen that rivers carry with them very rich and fertile soil which the farmers prefer because the amount of crop and the quality of crop is much better than they can get in any other place. The civilization of ancient Egypt as well as the Indus valley civilization were totally dependent on the Tigris and the Indus river respectively, as far as irrigation was concerned. Seasonal flooding always brings with it new fertile soil for irrigation.