What Does the Command Mount -A Do

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.