Why was the Nile Delta so important in the history of Egypt

A. Because it is not only the intersection of Africa, Asia and Europe but the important city Cairo stands on the Nile River, too.
Because its black soil has made it the foundation stone of 7,000 years of Egyptian history and its position is of great strategy.
C. Because people there mainly grow crops, raise domesticated animals, fish and their lifestyle shows they live on the river.
D. Because long before the pharaohs built the pyramids, Egypt's glory was the agricultural wealth of its delta.