Correct Option
Cameroon is a constituent country of the Congo Basin. The Congo Basin is globally recognized as the second-largest drainage basin, surpassed only by the Amazon Basin. Its geographical extent primarily encompasses six nations: the Democratic Republic of the Congo (DRC), the Republic of the Congo, the Central African Republic, Cameroon, Gabon, and Equatorial Guinea.
Incorrect Options
Nigeria (b) is located to the west of the Congo Basin and is predominantly part of the Niger River basin.
South Sudan (c) is largely situated within the Nile Basin.
Uganda (d) also belongs to the White Nile Basin, rather than the Congo Basin.