Which type of alarm will detect a moving object?

A motion detector is specifically designed to identify movement within a designated area. It typically uses infrared sensors, microwave sensors, or other technologies to sense changes in the environment, such as the heat emitted by a moving body or the movement of an object across its field of vision. When motion is detected, the device triggers an alarm or notification.

This capability makes motion detectors essential for security systems where monitoring for intruders or unauthorized movement is crucial. They can cover large spaces and are often used in conjunction with cameras and other security measures to enhance overall protection. In contrast, the other options listed either do not detect movement or are used for different types of monitoring, thereby reinforcing the specific role of motion detectors in security applications.