A system administrator will be migrating a server from AIX 5.1 to AIX 5.2 and is uncertain if the application running on the server will function properly after the migration. What is the fastest way to return to the previous AIX level if the application does not work？（）

• A、Use base media to restore system to AIX 5.1.
• B、Use an alt_disk_install and boot back to the AIX 5.1 rootvg.
• C、Make a mksysb of the original AIX to restore back to the AIX 5.1 level.
• D、Perform the AIX 5.2 upgrade using update_all with the commit option and reject filesets to return to AIX 5.1.