The Head Office of The International Court of Justice is situated in

The seat of the International Court of Justice (ICJ), the UN's principal judicial organ, is expressly fixed at The Hague by Article 22 of its own Statute, and the Court has occupied the Peace Palace there since it began work -- distinct from where other principal UN organs, such as the Secretariat, are seated.

Applying this to the item: the Head Office of the ICJ is therefore located in The Hague, Netherlands, where the Court has sat since 1946.

• Geneva houses the headquarters of several United Nations entities working in health, labour, and refugee protection (e.g. WHO, ILO, UNHCR), not the ICJ.

• New York houses the UN Secretariat, General Assembly, and Security Council -- the UN's political and administrative organs -- not its judicial organ.

• Paris houses UNESCO, the UN's education, science and culture agency, not the ICJ.

None of the other three cities host a principal judicial organ of the UN, so The Hague is the only option consistent with the ICJ's own Statute.