What command mounts all filesystems listed in /etc/fstab with the option auto set?

The command that mounts all filesystems listed in /etc/fstab with the option auto set is indeed the one that uses the syntax mount -a. When executed, this command reads through the entries in the /etc/fstab file and mounts all filesystems that are enabled to automatically mount, as indicated by the "auto" option.

This functionality is particularly important for system initialization and management tasks, where multiple filesystems need to be mounted at once without requiring individual commands for each. The command effectively streamlines the process of ensuring that all specified filesystems are active and available.

While other options mentioned relate to filesystem operations, they do not serve the specific purpose of mounting all configured filesystems in one command as mount -a does. For instance, the command mount by itself would require additional arguments to specify what is to be mounted. The term automount refers to a different mechanism that automatically mounts filesystems on demand rather than at system startup. The term mountall does not exist as a standard command in Linux for this purpose. Thus, the clarity and specificity of mount -a makes it the correct choice in this context.