What is the BEST alternative if you discover that a rootkit has been installed on one of your computers?

Copying system files from another system does not guarantee removal of all rootkit components, especially those embedded in the registry, firmware, or non-OS locations.

Trap and trace is a network monitoring technique used to identify attackers, not a method to remediate a rootkit infection on a host.

Deleting visible rootkit files is ineffective because rootkits use stealth techniques to hide their presence and may have hidden components that survive deletion.

Reloading from a previous backup is risky because the backup may predate discovery but not the infection, meaning the rootkit could already be present in the backup image.

Rootkits replace or hook into core OS components, making the infected system untrustworthy for any in-place recovery. Reloading from known good media (a clean OS installation source) guarantees no rootkit code persists, as it bypasses any potentially compromised files, backups, or system utilities on the infected machine.