While using the smit install_remove menus to remove some filesets on an AIX 5.3 server， a system administrator notices the /usr filesystem is now unnecessarily large.  Which of the following actions will reduce the size of the /usr filesystem （）

• A、Backup， unmount， remove， recreate and restore the filesystem.
• B、Boot from mksysb tape and select Shrink filesystems on restore.
• C、Unmount， run defragfs /usr and the reducefs -size n /usr commands.
• D、Update the /image.data file with the desired size for /usr and reboot the system.