Explanation:

• The Congo Basin is the second-largest river basin in the world. It spans across six central African nations: Cameroon, Central African Republic (CAR), Democratic Republic of the Congo (DRC), Republic of the Congo, Equatorial Guinea, and Gabon.
• Cameroon’s southeastern portion drains directly into the Sangha River system, a major tributary of the Congo River.
• Nigeria, South Sudan, and Uganda fall under the Niger, Nile, and East African rift drainage basins respectively.