Mark each statement if it was a factor in the decline of sumer. a. nomads invaded sumerian city-states. b. salinization of the soil occurred. c. the cultivated soil had poor drainage.

All of the statements listed here are factors in the decline of Sumer. They are all somewhat linked to each other, in that due to the failure of the soil there was less food available to the people of Sumer - something which had not previously ever been an issue, in fact they were able to grow more crops than they actually needed. This of course meant that the invaded cities were already weakened.

What does this mean ? ?