Which item is NOT one of the three basic components of a burglar alarm system?

• A. Sensing devices
• B. Control unit
• C. Reporting device
• D. Battery backup

Answer: (D)

The basic structure of a burglar alarm system centers on three functional parts: sensing devices that detect intrusions, the control unit (panel) that processes those signals, and the reporting device that alerts occupants or a monitoring service. Battery backup is a power-supply feature, not a direct function of sensing, processing, or reporting. It keeps the system running during a power outage, but it doesn’t itself perform detection, decision-making, or alerting. So battery backup is not considered one of the three basic components.