Why did so many early civilzations arise near rivera valleys

How was life different for poor romans and wealthy romans? a. the wealthy lived in highly populated urban areas, and the poor lived in villas in the country. b. the poor lived on the docks by the sea, and the wealthy lived in highly populated urban areas. c. the wealthy women sold clothing and jewelry in shops, and the poor women managed the farms. d. the wealthy lived in villas in the summertime, and the poor lived in highly populated urban areas.