Which of the following is an audible notification option used in security systems?

• A. Self-contained sirens
• B. Glass-break sensors
• C. Motion detectors
• D. Smoke detectors

Answer: (A)

Audible notification devices are those that actually emit sound when the alarm is active. A self-contained siren has its own built-in sounder and power, so it can produce a loud alarm directly from the unit to alert occupants and deter intruders. The other options are detectors or sensors that signal when something happens but do not themselves produce the audible alarm: glass-break sensors detect a breaking window and raise the alert; motion detectors sense movement and trigger the system; smoke detectors provide a fire alarm sound, but they are primarily for fire protection, not the security system’s intruder notification. So the best answer is the self-contained siren.