What does the command mount -a do?
A. It ensures that all file systems listed with the option noauto in /etc/fstab are mounted.
B. It shows all mounted file systems that have been automatically mounted.
C. It opens an editor with root privileges and loads /etc/fstab for editing.
D. It ensures that all file systems listed with the option auto in /etc/fstab are mounted.
E. It ensures that all file systems listed in /etc/fstab are mounted regardless of their options.