History was a driving force behind such migration, since humans tended to move to new territory when they lacked food, shelter, or other resources--meaning that most of the conflicts throughout history have been driven by the same forces that drove migration out of Africa.
The Three Gorges Dam is located along the Yangtze River.
Answer:
I'm going with B kinetic energy from ocean currents
From an overall perspective, A would be the best answer. Since the Nile River has always been one of the biggest rivers in history, it would most likely sustain life for the people. As well as the mediterranean, people for thousands of years relied on the Mediterranean Sea for their food and even their transportation.