Which of the following represents an example of a preventive control for IT personnel?

The implementation of a badge entry system for the IT facility is a key example of a preventive control aimed at protecting IT personnel and resources. This control serves to restrict access to authorized individuals only, thereby reducing the risk of unauthorized entry which could lead to data breaches, theft, or damage to sensitive IT infrastructure.

By requiring personnel to use their badges to access the facility, it ensures that only those with proper authorization can enter, effectively mitigating threats from malicious actors and enhancing overall security. Such preventive measures are crucial in safeguarding not just the physical IT environment but also the data and systems within.

In contrast, while options like a security guard or a fire suppression system offer important security and safety benefits, they are more aligned with reactive or detective controls rather than outright preventive measures. An intrusion detection system, although essential for monitoring and alerting to potential threats, also does not actively prevent unauthorized access but rather identifies it after the fact. Thus, the correct answer stands out because it directly prevents security breaches through controlled access.