Which of the following interior sensors can be defined as both passive and active?

Infrared sensors can function as both passive and active types:

Passive Infrared (PIR): Detects natural heat (infrared radiation) from people or animals.

Active Infrared: Emits infrared beams and detects interruptions in the beam (e.g., photoelectric sensors).

This dual use allows infrared to serve a variety of security applications.

A (Microwave) is strictly active.

C (Vibration) and D (Pressure) are passive only.