Which of the following represents a loss of essential function?

The correct answer reflects the concept that an essential function in a system often includes its ability to provide safety, security, or protection against threats. "Loss of protection" implies that the system can no longer safeguard its critical assets or operations, which is fundamentally detrimental and can compromise the entire integrity and reliability of the system.

This highlights the idea that without the protective measures in place, vulnerabilities can be exploited, leading to potential breaches or failures. An essential function must ensure that the elements vital to the system’s operation are safeguarded against various types of risks, including unauthorized access or damage.

In contrast, while the other options involve significant aspects of system function, they do not directly address the idea of losing protective capabilities. Loss of resources refers more to the availability of assets rather than their protective features. Loss of feedback touches on the system’s ability to monitor and adjust based on input but does not equate to a direct threat to function. Loss of data integrity is critical, but it pertains specifically to the reliability of data rather than the overall protective capacity of the system.