Which branches comprise the military department?

The military department comprises the Air Force, Army, Navy, and Marine Corps. These four branches are the primary components of the Department of Defense and are responsible for the nation's defense and military operations. Each branch has its own unique mission and capabilities, contributing to the overall strength and readiness of the U.S. military.

The inclusion of all four branches highlights their cooperative roles in maintaining national security and responding to various military needs, from land operations to air superiority and naval dominance. Understanding the distinctions among these branches is crucial for grasping how they collaborate and function within the broader framework of national defense.

The other options do not accurately reflect the complete set of military branches involved in the military department, omitting one or more of the key branches, which are essential for a comprehensive view of U.S. military structure.