Which alarm system type does not activate a bell/siren circuit?

The correct answer identifies a system type specifically designed to function without activating a bell or siren circuit during operation. In the case of a Type 22 alarm system, it is often used for purposes such as monitoring and providing alerts without the necessity for an audible alarm. These systems typically serve applications where a stealthy approach is preferred, such as silent intrusion detection.

Type 22 systems also may utilize alternative alert methods, such as sending notifications to a central monitoring station or alerting a user through other means without causing external noise disruption. This makes them suitable for environments where discretion is important or where it is necessary to avoid drawing attention to the alarm event.

In contrast, the other types generally are configured to engage audible alerts as part of their standard operation. This is crucial for immediate notification to those nearby and serves as a deterrent to potential intruders. Thus, Type 22 stands out for its specific design choice that omits the activation of a bell or siren.