The answer is Nile.
The Nile is the longest river in the world, and it flows north for over 4,000 miles through Sudan and Egypt before emptying into the Mediterranean Sea. The Nile has been a vital source of water and transportation for people living in its basin for thousands of years.
The other answer choices are incorrect:
The Congo River is located in Central Africa and flows west into the Atlantic Ocean.
The Kalahari Desert is located in Southern Africa.
The Aswan Dam is a hydroelectric dam located on the Nile River in Egypt.