What is the collar device for an E-1 in the Navy?

The collar device for an E-1 in the Navy is indeed represented by the choice stating "None." An E-1, also known as a seaman recruit, does not wear any collar insignia, which distinguishes this rank from higher ranks that do have specific insignia.

In the Navy, collar devices are a form of insignia worn by enlisted personnel, and each rank has its own unique device. E-1 being the most junior rank, signifies the entry-level position for recruits, hence the absence of any insignia. This is a way of indicating the basic status of the individual in military hierarchy. As recruits progress in rank, they will begin to wear devices that reflect their rank, such as chevrons or other insignia.