A Coast Guard message regarding an aid to navigation that is off-station is preceded by what?

A Coast Guard message regarding an aid to navigation that is off-station is preceded by "Security." This term is used to indicate that there is information concerning the safety of navigation that mariners need to be aware of. By using "Security," the message communicates that it is important for vessels in the vicinity to listen closely because it pertains to navigating safely in the area.

The other options, while related to emergency communications, are used under different circumstances. "Emergency" and "Mayday" are typically reserved for urgent situations requiring immediate assistance, which is not the case with routine information about navigation aids. "Attention" is not a standardized term within this context, further distinguishing "Security" as the appropriate precursor for information about off-station navigational aids.