What is 4-step protection in intruder alarm systems?

• A. An intruder cannot take four 24-inch steps in any direction without being picked up by a motion sensor
• B. Four locks on entry doors are used in sequence
• C. Four independent zones must be activated before alarm triggers
• D. A four-year sensor warranty is required for protection

Answer: (A)

Four-step protection focuses on movement being detected by motion sensors as a person advances through a space. The idea is that the area is covered so tightly that any attempt to move a short distance—about four steps, roughly 24 inches in any direction—will trigger a sensor. This means the intruder cannot progress without at least one sensor picking up the activity, which is the core purpose of this protection approach.

That’s why the statement describing an intruder’s movement being limited to four 24-inch steps before a motion detector is triggered best captures the concept. It directly reflects how four-step protection uses dense sensor coverage to ensure detection as movement occurs. The other options describe things unrelated to this movement-based detection approach—such as locking doors in sequence, activating multiple zones, or warranty requirements—so they don’t describe four-step protection.