The Commission on Mediation, Conciliation and Arbitration is an organ of

Analyze the question: The question asks which international organization has a body called the "Commission on Mediation, Conciliation and Arbitration."

Explain the concept: Regional and international organizations set up special organs to settle disputes peacefully. The Organization of African Unity (OAU), now the African Union (AU), created the Commission of Mediation, Conciliation and Arbitration under Article XIX of its 1963 Charter in Addis Ababa. Its purpose was to settle disputes between African member states peacefully, without war.

Step-by-step solution:

1. United Nations: Its main organs are the General Assembly, Security Council, ECOSOC, Trusteeship Council, International Court of Justice, and Secretariat. It has no commission by this name. The UN's court is the ICJ, and it handles dispute settlement differently.
2. Commonwealth: Its organs include the Commonwealth Secretariat and the Heads of Government Meeting. It does not have this commission.
3. OPEC: Its organs are the Conference, Board of Governors, and Secretariat. It is concerned with petroleum policy, not mediation.
4. African Union (formerly the OAU): The Commission of Mediation, Conciliation and Arbitration was established in the OAU Charter of 1963. The AU is the successor to the OAU, so the commission is associated with it. The AU later developed the Peace and Security Council to handle conflicts, but the commission remains the classic answer to this question.

Answer: The correct option is **D.

Exam tip: Remember the OAU/AU organs: the Assembly of Heads of State and Government, Council of Ministers, General Secretariat, and the Commission of Mediation, Conciliation and Arbitration. When you see "Mediation, Conciliation and Arbitration" in JAMB, think Africa.