Which command forcibly unmounts this file system?

The disk slice /dev/dsk/c2t2d0s3, which has the /opt/software file system mounted, is starting to
report errors that indicate it might crash soon. It is imperative that the file system is unmounted
and the disk taken offline quickly. A check indicates that a number of people are accessing this file
system.
Which command forcibly unmounts this file system?

A.
umount -f /opt/software

B.
unmount -f /dev/dsk/c2t2d0s3