"how did egyptian irrigation differ from mesopotamian irrigation? "

Both Egyptian and Mesopotamian societies were dependent on agriculture and these operations were supported through vast and developed irrigation systems. However, the main difference in these systems comes from the source of water, where Egyptians had a steady source of water from the Nile and farmed alongside the river according to the flooding patterns, the Mesopotamians were forced to use a system of levees, dams and artificial channels to collect rainwater from mountainous regions and transport to agricultural areas. 

The answer should be b.