What distinguishes a security alarm from a surveillance system?

The distinguishing factor of a security alarm compared to a surveillance system lies in their fundamental purposes and functions. A security alarm is designed primarily to detect and alert personnel about unauthorized access or breaches in a defined area. Its main role is to activate in response to triggers, such as motion detectors or unauthorized entry, thus providing an immediate alert to potential threats.

In contrast, a surveillance system is used for monitoring and recording activities within a designated area. These systems maintain ongoing observation, typically through cameras, allowing for real-time monitoring and later review of recorded footage. This not only aids in crime prevention but also assists in investigations after an incident has occurred.

The other options do not accurately reflect the primary functions of security alarms and surveillance systems. For example, while certain security alarms may contribute to fire safety, that is not their sole function, and surveillance systems extend beyond crime prevention to include operational monitoring. The notion that alarms are strictly exterior and surveillance systems strictly interior is also misleading, as both can be utilized in various configurations based on security needs. Therefore, option B aptly captures the essence of the difference between these two security measures.