A bank set up a new server that contains customers' PII. Which of the following should the bank use to make sure the sensitive data is not modified?

File integrity monitoring (FIM) is the best choice because it specifically detects unauthorized changes to files, including those containing sensitive PII. FIM tools create a baseline of file attributes (like hashes, size, and permissions) and then continuously monitor for any deviations from that baseline, alerting administrators to potential tampering or corruption. Full disk encryption protects data at rest from unauthorized access if the physical disk is stolen, but it doesn't prevent modification once the system is running and the disk is decrypted. Network access control (NAC) manages which devices and users can connect to the network, but it doesn't directly monitor file integrity on a server. User behavior analytics (UBA) identifies anomalous user activities, which could indicate a compromise, but it's a reactive measure and doesn't directly prevent or detect file modification in the same way FIM does.