Which rank corresponds to O-1 in the Marine Corps?

The rank that corresponds to O-1 in the Marine Corps is 2nd Lieutenant. In the United States military, the Officer ranks are categorized into different pay grades, known as the "O" scale, where O-1 is the entry-level rank for commissioned officers.

In the Marine Corps, an officer is promoted to 2nd Lieutenant upon commissioning and is the lowest rank of officers. This rank signifies that the officer has completed their training and is starting their service in a leadership position, albeit at a junior level. As they gain experience and fulfill certain requirements, they can be promoted to the next rank, which is 1st Lieutenant (O-2).

Choosing 2nd Lieutenant as the answer reflects an understanding of the rank structure within the Marine Corps and the promotions that follow. Other choices such as Captain (O-3) and Major (O-4) are higher ranks that follow the 2nd Lieutenant rank in the officer hierarchy, while 1st Lieutenant (O-2) is a subsequent rank that comes after O-1.