Which of the following is not a principal organ of United Nations Organisation ?

Article 7 of the UN Charter establishes six principal organs: the General Assembly, the Security Council, the Economic and Social Council, the Trusteeship Council, the International Court of Justice and the Secretariat. The Commission on Human Rights was a subsidiary body set up by the Economic and Social Council, not a principal organ; it was replaced in 2006 by the Human Rights Council, a subsidiary organ of the General Assembly.