Which type of detector is inappropriate for use in an intrusion system regarding supervision?

In the context of intrusion detection systems, the mention of "supervision" refers to the ability of a detector to monitor its operational status and provide alerts when it is malfunctioning or being compromised. Supervised PIR (Passive Infrared) sensors, dual technology sensors, and wired contact sensors have built-in mechanisms to verify their functionality. They can inform the system if they are operational, ensuring that they are not failing silently, which is crucial for security.

The choice indicating "NO unsupervised detectors" points out a type of detector that doesn’t provide any feedback about its operational status. Such unsupervised devices can be problematic because they may malfunction or become inactive without the system being aware, thus creating potential vulnerabilities. If a detector fails and does not notify the system administrator, the integrity of the security system can be compromised, which can lead to a breach or failure to detect an intrusion.

Therefore, the emphasis on avoiding unsupervised detectors in intrusion systems aptly highlights the importance of supervision and functionality in maintaining a robust security posture. The other options represent types of sensors or systems that typically provide supervision, emphasizing their necessity in effective intrusion detection setups.