Concept:Nigeria provided the leadership and venue for the treaty that founded ECOWAS, making it a primary architect of the organisation.
Explanation:ECOWAS, the Economic Community of West African States, was created on May 28, 1975.
The founding treaty was signed in Lagos, Nigeria, which shows the country's central role.
General Yakubu Gowon of Nigeria promoted this initiative together with President Eyadéma of Togo.
Nigeria hosts the main headquarters of ECOWAS in Abuja, while the financial headquarters is in Lomé, Togo.
These facts clearly link Nigeria to the creation of ECOWAS rather than OPEC, the UN, or the Commonwealth.
Answer:A. ECOWAS