What role do "motion detectors" play in a security system?

Motion detectors are integral components of a security system because they are specifically designed to detect movement within monitored areas. Their primary function is to sense activity in a designated space, which allows the security system to respond appropriately, such as triggering alarms or sending alerts when unauthorized movement is detected.

These devices utilize various technologies, such as passive infrared, microwave, or dual-technology sensors, to identify motion based on changes in the environment. For instance, passive infrared detectors sense changes in heat signatures that occur when a person or object moves across their field of view. By accurately capturing these movements, motion detectors help ensure the security and safety of premises by alerting property owners or security personnel of potential intrusions.

The other options relate to different aspects of security technology but do not represent the function of motion detectors.