What is the reply given by the SNSI or NSI after the command "Attention on Deck"?

When the command "Attention on Deck" is given, it signifies that individuals should immediately assume a position of direct attention. The appropriate reply from the Senior Naval Science Instructor (SNSI) or Naval Science Instructor (NSI) is "Carry on." This response indicates that personnel can resume their normal activities while maintaining a level of respect and readiness. It effectively transitions the setting from formal attention to a more relaxed posture, allowing cadets to continue their duties or conversations without the rigid formality that "Attention on Deck" requires.

The other responses do not correctly fit the context of this command. For example, "Stand by" suggests a readiness to receive further instructions, "At ease" would allow for a casual posture without the expectation of immediate duty, and "Fall in" directs individuals to form ranks, which is not necessary once the command has been acknowledged and the response given. "Carry on" is the only option that appropriately reflects the shift from formal acknowledgment of authority back to regular activity.