In ARPA, what is the primary function of the guard zones?

The primary function of guard zones in ARPA (Automatic Radar Plotting Aids) is to signal alarms based on target proximity. Guard zones are predefined areas set around the vessel to monitor the vicinity for potentially hazardous targets. When an object enters a guard zone, the system activates alarms, alerting the operator to take necessary actions to avoid collisions. This functionality is crucial for enhancing situational awareness and ensuring safety by providing real-time alerts about nearby vessels or obstacles.

The other options, while relevant to the operation of ARPA, do not capture the specific role of guard zones. Tracking moving targets is an integral part of ARPA's capabilities, but it does not solely focus on proximity alerts. Visual representations of target positions are important for navigation; however, this pertains more to the overall display and tracking functions rather than the specific purpose of guard zones. The notion of eliminating target swapping addresses a different aspect of radar tracking accuracy and management, but it is not the primary function of guard zones.