The Nile is propably the answer they want but other rivers such as the Limpopo has also supported civalizations (see Mapungubwe)
The most common one was the Egyptian's.
River Niger
The Orange River is probably the main river system in South Africa, although the Limpopo is also a major system
River Niger
It's the Congo river.
The Orange river is the largest river. The Vaal river is significant
The nile river
There were two main rivers in the Indus Valley Civilization; The Ghaggar-Hakra and the Indus.
because water is main source that can be easily available
the biggest is the nile river in Africa Egypt
the fertile river valleys which favord agriculture.
Africa is one of the largest continents on the planet and has many rivers on it. There is, however, no river in Africa that starts with the letter "Q".