Which rank is identified as O-1 in the Navy?

In the Navy, the rank identified as O-1 is Ensign. The designation "O" refers to officer ranks within the military pay grade system, where O-1 is the entry-level officer rank. This is significant as it represents the initial step for commissioned officers in their careers, distinguishing them from enlisted personnel, which are designated as E ranks.

The rank of Ensign has specific responsibilities, including serving as a division officer and assisting in the administration and leadership of their unit, thereby contributing to their growth as leaders. This foundational rank is the starting point for many officers who will progress through the various naval ranks based on experience and performance.

Other choices represent ranks that are either higher (such as Lieutenant and Lieutenant Commander) or belong to the enlisted category (like Senior Chief Petty Officer), thus reinforcing the correctness of the selection for O-1 being an Ensign.