Final answer:
The best tool for regular archiving of information on a PC is the Backup tool, because it is designed specifically for creating copies of data to prevent loss.
Step-by-step explanation:
The best system tool to perform a regular archiving of information on a PC from the options given would be C. Backup. This is because the primary purpose of a backup tool is to create copies of data so that these additional copies may be used to restore the original after a data loss event.
Tools like ROBOCOPY and XCOPY are more suited for copying files from one location to another and do not have the same comprehensive features and simplicity for regular archiving that a dedicated backup solution provides. System Restore, on the other hand, is used for recovering system files and settings to an earlier state, not for archiving personal data.