What rank does O-4 represent?

The rank represented by O-4 is Major. In the context of the military ranking system, "O" designates commissioned officer ranks, with the number indicating the pay grade. O-4 is specifically assigned to the rank of Major in the Army, Marine Corps, and Air Force, and is also aligned with the rank of Lieutenant Commander in the Navy and Coast Guard.

The rank of Major typically follows the rank of Captain (O-3) and precedes the rank of Lieutenant Colonel (O-5). Therefore, the selection of Major as the correct rank for O-4 is rooted in this established hierarchy within the military structure. Understanding the classification and progression of officer ranks is crucial for recognizing the responsibilities and authority associated with each position.