Which of the following is an example of a physical security threat?

The selected answer is correct because it identifies a tangible and observable threat related to physical security. The theft of hardware or sensitive data from a physical location directly compromises the integrity and availability of the organization's assets. This type of threat stems from the physical environment, where unauthorized individuals gain access to facilities and remove or damage hardware and sensitive information, thereby posing a significant risk to an organization’s operations and reputation.

In contrast, the other options represent different categories of security threats. Malware infecting a server is a cyber threat that involves malicious software affecting digital systems rather than a physical intrusion. Unauthorized access through network protocols pertains to digital security vulnerabilities that can be exploited remotely, again not involving physical entry or interaction with tangible assets. Similarly, social engineering attacks targeting employees rely on psychological manipulation rather than physical means, making them a type of human factor vulnerability rather than a physical security threat. Thus, the theft of hardware or sensitive data distinctly exemplifies a physical security threat.