Concept:ECOWAS institutions perform different functions, and the approval of treaties and agreements belongs to its supreme organ, the Assembly of Heads of State and Government.
Explanation:The Assembly of Heads of State and Government is the highest decision-making authority in ECOWAS.
It is composed of the Heads of State and Government of all member states.
According to the ECOWAS Treaty, the Authority has the power to amend the treaty and approve all important agreements and conventions of the Community.
The Secretariat, on the other hand, handles the routine administration and implementation of Community decisions.
The Council of Ministers makes recommendations and supervises the functioning of the Secretariat, but it does not approve treaties.
The ECOWAS Tribunal is a judicial body that settles disputes among member states, institutions, or individuals.
Because only the supreme political organ can commit all member states to new international obligations, the responsibility of approving treaties and agreements rests with the Assembly of Heads of State and Government.
Answer:D. Assembly of Heads of State and Government.