Which best describes the purpose of an indicating device?

An indicating device is primarily designed to provide a local warning when an alarm condition occurs. This function is crucial in alerting occupants within a building or area to take appropriate action in response to the alarm, such as evacuating or preparing for further emergency response. Indicating devices include sound alarms, visual indicators like strobe lights, and other means to ensure that the alarm is noticed and understood by individuals present.

While other options describe important functions within the realm of fire safety and emergency response, they do not accurately represent the specific purpose of indicating devices. For example, triggering a facility lockdown pertains to security measures, activating a sprinkler system relates to fire suppression rather than indication, and monitoring temperature levels is more aligned with detection systems than with the primary role of indicating devices. Thus, the best description of the purpose of an indicating device is that it warns locally of an alarm.