Concept:Nigeria belongs to several international organizations, both within Africa and globally.
Explanation:Nigeria is a founding member of the Economic Community of West African States (ECOWAS), which promotes regional cooperation in West Africa.
It is also a member of the Organisation of African Unity (OAU), now known as the African Union, and the United Nations Organization (UNO).
The country is not a member of the North Atlantic Treaty Organization (NATO) or the Organization of American States (OAS).
Among the options, only the set containing OAU, UNO and ECOWAS correctly lists organizations Nigeria belongs to.
Answer:B. OAU, the UNO and ECOWAS