What sign must be displayed if a fire alarm system is not monitored by a supervising station?

The correct answer emphasizes the importance of communication in the event of a fire when a fire alarm system is not monitored by a supervising station. When the alarm sounds, it serves as a critical signal for occupants to take action to ensure their safety. If the system is not connected to a supervising station, it means there is no automatic notification to emergency services. Therefore, the clear instruction to call the fire department immediately is vital for ensuring that help is alerted without delay.

Providing such guidance helps occupants understand that their immediate response is crucial for their safety and that of others in the building, thereby reducing response times in emergency situations. This requirement aligns with safety codes and regulations that prioritize occupant safety and effective emergency response protocols.

The alternatives presented do not carry the same urgency or clarity regarding the need for immediate action when the alarm sounds. While some suggest notifying the fire department, they may not offer explicit instruction tailored to the context of a non-monitored system, which is why the first response stands out as the most appropriate.