One important difference between the nile river valley and mesopotamia was a) the nile was the center of all major religious ceremonies in egypt, but mesopotamians did not practice an organized religion. b) the nile flooded at the same time every year as opposed to the sporadic and unpredictable flooding of the tigris and euphrates rivers. eliminate c) the nile did not produce fertile soil in the same way that the tigris and euphrates did, forcing egyptian farmers to practice pastoralism. d) the nile is shorter than both the tigris and euphrates rivers, forcing egyptians in the southern part of egypt to use irrigation channels called qana