Which of the following is not true about intrusion detection systems (motion detectors, vibration sensors, light beams)?

Which of the following is not true about intrusion detection systems (motion detectors, vibration sensors, light beams)?

A.
They require human response

B.
They cause a lot of false alarms

C.
They depend on a constant power supply

D.
They are foolproof

Explanation:
Intrusion detection systems require someone to respond when they
alarm, are sensitive thus cause many false alarms, and require a constant power
supply. They are not foolproof, nothing is.