What term is used for the military branches that are designated by the President and Secretary of Defense?

The term that accurately describes the military branches designated by the President and Secretary of Defense is "Military Departments." This term specifically refers to the distinct branches of the armed forces—such as the Army, Navy, Air Force, and Marine Corps—as organized under Title 10 of the United States Code. Each Military Department operates under the authority and direction provided by the President as the Commander in Chief and the Secretary of Defense, who oversees the overall defense policy and planning.

The other options refer to different aspects of the military structure. "Armed Forces" is a general term encompassing all branches collectively but does not specify the hierarchical organizational structure. "Combat Support Agencies" refer to certain entities that provide advice, support, and assistance to military operations but are not classified as Military Departments. "Combatant Commands" denote specific operational commands led by combatant commanders responsible for managing forces in particular geographical or functional areas, but they do not represent the branches as defined by Military Departments.