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

nouidchk is not a recognized fstab mount option and has no defined behavior for controlling user mount permissions.

alluser (as written) is not a valid fstab option; the closest valid option is 'users' (plural), which allows any user to both mount and unmount the device regardless of who originally mounted it.

Adding the 'user' option to a filesystem entry in /etc/fstab permits any unprivileged user to execute mount and umount commands on that filesystem. This is the accepted method for allowing access to removable devices like CD-ROMs and floppy drives without requiring root privileges for every operation.

The 'auto' option causes the filesystem to be mounted automatically at boot time and has no effect on whether regular users can mount or unmount it.