An O-1 in NJROTC is represented by which collar device?

In NJROTC, the rank of O-1, which designates an Officer, is represented by a single gold bar as the collar device. This specific insignia is a universal symbol of the O-1 rank across many military branches, including the NJROTC program. The use of just one gold bar distinguishes it from higher officer ranks, which have additional bars or symbols indicating their seniority.

The reasons for the other options being incorrect relate to the number of bars depicted: two attached gold bars are associated with the O-2 rank, three attached gold bars correspond to higher ranks still within the officer category, making those choices unsuitable for representing an O-1 in NJROTC. Hence, the collar device for an O-1 clearly and accurately is a single gold bar, signifying the entry-level rank of commissioned officer.