Concept:ECOWAS has a fixed set of organs under its Treaty, and the "Conference" is not one of them.
Explanation:The Economic Community of West African States (ECOWAS) operates through clearly recognised organs.
These include the Authority of Heads of State and Government, the Council of Ministers, the Community Parliament, the Community Tribunal, and the Secretariat.
The Community Tribunal is a valid organ that settles disputes among member states.
The Council of Ministers is also a valid organ that oversees the functioning of the community.
The Secretariat, now known as the ECOWAS Commission, is equally a valid organ.
However, there is no organ called the "Conference" anywhere in the ECOWAS structure.
Therefore, the Conference is the organ that is not included in ECOWAS.
Answer:D. Conference