Which command-line tool should a technician use to repair corrupted system files on a Windows 10 PC?

The command-line tool that a technician should use to repair corrupted system files on a Windows 10 PC is the System File Checker, commonly known as "sfc." This utility scans the integrity of all protected system files and replaces corrupted or incorrect versions with the correct Microsoft versions. By running "sfc /scannow," the technician can initiate a comprehensive scan to identify and resolve issues with critical system files, which can help restore the system to a stable operating state.

The other tools mentioned serve different purposes. For instance, "chkdsk" is typically used for checking the file system integrity and will fix logical file system errors but does not specifically target system files. "fsck" is a similar tool used in Unix/Linux environments for checking and repairing file systems, not applicable to Windows. "diskpart" is a command for managing disk partitions and does not address file system corruption or repair system files at all.