Which of the following ranks is equivalent to O-3?

The rank that is equivalent to O-3 is Captain. In the officer rank structure, O-3 represents the third level of commissioned officers, and this designation is commonly associated with the rank of Captain in various military branches. For example, in the U.S. Army, Air Force, and Marine Corps, an officer holding the rank of Captain is classified as O-3, indicating they have achieved a certain level of experience and responsibility.

Although Lieutenant Commander, Lieutenant Junior Grade, and Ensign are all ranks in the naval structure, they correspond to different O-level classifications. A Lieutenant Commander is an O-4, which is a next higher rank, while a Lieutenant Junior Grade is O-2, and an Ensign is the lowest officer rank at O-1. Understanding this hierarchy is crucial for recognizing the progression and differences in ranks among the military branches.