L'/L.........est le plus long fleuve d'Afrique.

The correct answer to the question regarding the longest river in Africa is the Nile. The Nile River is not only the longest river in Africa but is often considered the longest river in the world. It flows through northeastern Africa, passing through countries such as Uganda, Sudan, and Egypt, finally emptying into the Mediterranean Sea. The total length of the Nile is approximately 6,650 kilometers or about 4,130 miles.

In comparison, the other rivers mentioned in the options are shorter:

• Niger River: This river is the third longest river in Africa with an approximate length of 4,180 kilometers (about 2,600 miles). It flows through countries such as Nigeria, Mali, and Niger.
• Congo River: Known for being the second longest river in Africa, the Congo River has an approximate length of 4,700 kilometers (about 2,920 miles). It flows through countries like the Democratic Republic of the Congo and the Republic of the Congo.
• Orange River: This river is much shorter, with an estimated length of 2,200 kilometers (about 1,367 miles). It mainly flows through South Africa and forms the border between South Africa and Namibia.

Thus, the Nile River is recognized as the longest river in Africa.