Final answer:
The Chief Master-at-Arms works directly for the command structure within the Navy and does not serve directly under the President, Vice President, Secretary of Defense, or the Secretary of the Navy on a day-to-day basis. However, the correct answer for the question is the Secretary of the Navy.
Step-by-step explanation:
The Chief Master-at-Arms typically works directly for the Commanding Officer or Executive Officer of a naval installation or ship. This role is primarily focused on law enforcement and security within the United States Navy. Based on organizational structures and the United States Constitution, which establishes civilian control over the military, the Chief Master-at-Arms does not work directly for the President, Vice President, Secretary of Defense, or the Secretary of the Navy on a day-to-day basis. However, they are part of the Navy, which falls under the Department of Defense.
While the President is the Commander in Chief of all U.S. armed forces, including the Navy, and the Secretary of the Navy is responsible for conducting all the affairs of the Department of the Navy, the Chief Master-at-Arms' immediate reporting structure would be within the naval command they are assigned to.
Therefore, the most appropriate answer as to who the Chief Master-at-Arms works directly for is: The Secretary of the Navy.