What might a sprinkler system's alarm bell indicate during a fire?

A sprinkler system's alarm bell is designed to convey critical information during a fire situation, and one of its primary functions is to alert occupants and responders when a sprinkler head has activated and water flow has begun. When a sprinkler head activates, it releases water to suppress the fire, and the alarm is triggered to notify everyone in the vicinity that the suppression system is actively working to control the fire hazard. This early warning is crucial for safety and helps direct firefighters to the appropriate area of concern, ensuring they can respond effectively.

The other options do not accurately describe the specific indication provided by the alarm bell during a fire. The interruption of the water supply, a need for maintenance, or smoke detection are managed by different system alerts or could involve other components of fire protection systems, but they would not directly correlate to the alarm bell's activation as a result of sprinkler head operation.