The correct answer to this open question is the following.
Describe how early river valley civilizations innovated to meet their needs.
Early river valley civilizations were smart and had to find a way to overcome the many obstacles that encountered
One of the needs was to grow crops to feed their families and could stay in one place definitely after so many years wandering, following herds to hunt them. That is why the innovation they developed was to create agriculture systems and to understand the flooding of the rivers so they could take advantage of the fertile soil left by the flooding.
That is why these civilizations grew and prosper. That was the case of the Sumerians, for instance, the oldest civilization on earth.
They settled in the middle of two major rivers: the Tigris and the Euphrates in the Middle East region, modern-day Iraq. There, they could establish powerful city-states such as Lagash, Nippur, Eridu, Uruk, Ur, and Kish.
