Question

fire alarm system buildings often have a fire alarm system. it is designed to detect a fire and sound an alarm. the system consists of (among others): smoke detectors manual activation points led flashing lights sirens if the alarm is activated, you are warned by sound and visual alarms to evacuate the premises. false alarm false alarms cause firefighters to respond for no reason. therefore, activating a fire alarm when theres no fire is a criminal offense, often punishable by heavy fines. what does a fire alarm system do? sends a silent alarm to the fire fighters when a fire has broken out. this is a phone system that you should use when a fire breaks out. detect a fire and sound the alarm by means of visual and sound signals. check

Explanation:

The text clearly states that a fire - alarm system is designed to detect a fire and sound an alarm using sound and visual signals to warn people to evacuate.

Answer:

Detect a fire and sound the alarm by means of visual and sound signals.