Final answer:
General John A. Lejeune was the 13th Commandant of the Marine Corps.
Step-by-step explanation:
The correct answer is C) 13th.
General John A. Lejeune was the 13th Commandant of the Marine Corps. He served in this position from 1920 to 1929. Lejeune played a crucial role in modernizing and expanding the Marine Corps during his tenure.