Which mount option must be used in the example /etc/fstab entry below, to ensure that a specific filesystem is not mounted when the system is booted? /dev/hdd /media/cdrom iso9660 __________,ro 0 0

Answer: noauto

Explanation:
There are auto and noauto options, auto option is used to mount the filesystem when system is booted automatically and to not mount use the noauto option.