The correct answer is C. Perform a clean installation . When ransomware has encrypted files and the organization does not pay the ransom, the priority is to remove all traces of malware and rebuild the system from a trusted state. Quentin Docter’s Complete Study Guide explains that in ransomware situations, remediation may not be possible because user files are encrypted. It further states that in cases where no one can be certain what the malware payload has done, the proper remediation might be to sanitize the drive and reinstall the operating system from an image or manually reinstall it. A recovery partition or Windows Recovery Environment repair may leave infected files, settings, persistence mechanisms, or damaged user data behind. Upgrading to Windows 11 does not guarantee malware removal. A clean installation removes the existing compromised OS and provides the best path to full operation, followed by restoring clean data from known-good backups.