In order for a monitoring system to be considered "fail safe" it must...

A monitoring system is considered "fail safe" when it takes steps to protect against failure by implementing automatic safety measures. Specifically, for a monitoring system associated with underground storage tanks, this means that if the monitoring system fails or is disconnected, it should automatically shut down the pumping system to prevent any potential leaks or hazards.

This is critical because, in the event of a failure, the primary goal is to avoid situations that could lead to environmental contamination or safety incidents. If the system does not shut down and continues to operate while compromised, it could result in serious consequences, including leaks of hazardous materials.

Other options provide valuable features for monitoring systems but do not meet the essential criteria for being classified as "fail safe." For instance, alerting the operator about a failure enhances safety but does not directly prevent potential risks from occurring if the operator is not present or capable of responding quickly. Self-diagnosing every 24 hours can improve system reliability but does not address immediate safety concerns when failures occur. Maintaining operational pressure is important for system functionality, yet it does not contribute to the fail-safe aspect related to failure response. Thus, only the option of shutting down the pumping system during a failure fulfills the fail-safe requirement effectively.