The correct answer is (d). None of the above can enforce the judgement of the International Court of Justice.
The International Court of Justice (ICJ) is the principal judicial organ of the United Nations. It settles legal disputes between states and gives advisory opinions on legal questions referred to it by authorized United Nations organs and specialized agencies.
The ICJ has no enforcement powers. It can only issue judgments, which are binding on the parties to the dispute. However, the ICJ has no means of enforcing its judgments. If a party fails to comply with a judgment, the ICJ can only refer the matter to the Security Council. The Security Council may then take action to enforce the judgment, but it is not obliged to do so.
The General Assembly and the Secretary-General of the United Nations also have no enforcement powers. The General Assembly can adopt resolutions calling on states to comply with ICJ judgments, but these resolutions are not binding. The Secretary-General can also make recommendations to states on how to comply with ICJ judgments, but these recommendations are not binding either.
The Security Council is the only organ of the United Nations that has the power to enforce ICJ judgments. However, the Security Council is often unable to take action due to the veto power of its five permanent members.