While using the smit install_remove menus to remove some filesets the 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 XXX /usr commands.
• D、Update /etc/filesystems with the desired size for /usr and reboot the system.