what is the major flaw in the sumerian system of canals that flowed through many different cities? a:a. cities located upriver could block the water flow for cities downriver. b:b. water was only available to the lucky few who lived next to the canals. c:c. no one could make money from the water because it was freely available to everyone. d:d. people who lived downriver could use all the water before it reached the cities upriver. turn in