Which of the following ranks is not part of the Marine JROTC O-4 to O-10 scale?

The rank of Admiral (Adm) does not belong to the Marine JROTC O-4 to O-10 scale because it is a rank specific to the Navy and Coast Guard. In the context of the Marine Corps, which is part of the Department of the Navy but has its own distinct ranks, the highest ranks on the O-4 to O-10 scale include Major General (MajGen), Colonel (Col), and Brigadier General (BGen).

The O-4 to O-10 ranks in the Marine Corps specifically include ranks such as Major (O-4), Lieutenant Colonel (O-5), Colonel (O-6), Brigadier General (O-7), Major General (O-8), Lieutenant General (O-9), and General (O-10). The inclusion of only Marine Corps ranks in this scale emphasizes the hierarchical structure that is specific to that branch of the military, whereas the rank of Admiral pertains to a different service altogether. Understanding this distinction helps reinforce the unique ranking systems of the different branches of the U.S. Armed Forces.