To allow a regular user account to mount and unmount a filesystem （for instance， a cdrom or floppy）， which option need to be added to the corresponding line in /etc/fstab？（）

A. software to predict the location of installed files and directories
B. software to predict the ownership and access rights to files and directories
C. users to predict the location of installed files and directories
D. users to predict how the filesystem should be formatted according to need

A. locate
B. which
C. find
D. query
E. whereis