Which statement was a factor in the decline of sumer choose all answers that are correct a- a drought caused poor crop production. b- nomads invaded sumerians city-states c- the cultivated soil had poor drainage. d- salinization of the soil occurred. asap!

Ancient Sumer declined, as all civilizations eventually do. In part this was caused by invasions of "barbarians," meaning the people in the next land. They also had a change of climate at that time, which reduced crop yields on lands that had already been over-worked. The resulting famine resulted in many people migrating to other lands.