Which statement best describes a fire alarm?

A fire alarm is fundamentally designed to detect conditions indicative of fire, such as smoke or high heat. This technology utilizes sensors that monitor various atmospheric changes, allowing for early warning in the event of a fire, which is critical for ensuring safety and facilitating timely evacuation. The proper functioning of a fire alarm can considerably reduce the risk of injury or loss of life during a fire emergency.

In contrast, alarms that detect vibrations or movement, typically associated with security systems, are not relevant to fire detection. Additionally, alarms aimed at preventing theft are specifically tailored to address burglary issues and do not have the capability to identify smoke or heat. A manual activation feature alone does not define a fire alarm since many systems have automated sensors to detect fire conditions without needing manual input. Thus, the correct answer accurately encapsulates the primary purpose and function of a fire alarm system.