The correct answers are A) Wars among the city-states plagued the Sumerians and C) As the fields of Sumer grew saltier, harvests were less plentiful.
The statements that were a factor in the decline of Sumer were the following: Wars among the city-states plagued the Sumerians, and as the fields of Sumer grew saltier, harvests were less plentiful.
We are talking about the oldest civilization known to men: the Sumerians. Sumeria was located in the middle of the Tigris and Euphrates Rivers, in what today is Iraq, in the Middle east region. They built impressive city-states such as Lagash, Ur, Uruk, and Kish. They learned how to grow crops using the flood of the rivers. However, a couple of factors that influenced the decline of Sumer were the wars among the city-states that plagued the Sumerians, and as the fields of Sumer grew saltier, harvests were less plentiful.