Final answer:
The President of the United States is authorized to approve the acceptance and wear of the United Nations Medal. This is within their role as the Commander in Chief of the US armed forces.
Step-by-step explanation:
In the context of the United States armed forces, the authority to approve acceptance and wear of the United Nations Medal falls to the President of the United States. This is because, as outlined in the Constitution, the President serves as the Commander in Chief of the Army and Navy of the United States. The approval supports the President's determination to take all necessary measures to repel any armed attack against the forces of the United States, as mentioned in the congressional resolution.
Related to the subject, one of the questions about the primary organs of the United Nations, the correct answer is 'd. World Congress', as it is not one of the primary organs of the UN. The primary organs are the Security Council, General Assembly, and Secretariat.