What triggers the alarm in a glass break sensor?

The correct answer is that vibration from the breaking glass triggers the alarm in a glass break sensor. These sensors are specifically designed to detect the frequency and intensity of vibrations that occur when glass shatters. When the glass breaks, the vibrations create sound waves that the sensor is calibrated to recognize as a signal for potential unauthorized entry or breach.

Other options do not initiate the alarm in a glass break sensor. The sound of an alarm clock does not match the specific frequency associated with breaking glass, making it ineffective as a trigger. The opening of a door is monitored by different types of sensors, such as door contacts or motion sensors, rather than a glass break sensor. Additionally, while movement within the vicinity can activate motion detectors, it does not pertain specifically to glass breakage detection, which relies solely on the vibrations caused by the glass itself breaking.