In addition to cat /proc/self/mounts, which other command can be used to display all currently mounted filesystems?

The command that correctly displays all currently mounted filesystems is 'mount'. It provides a straightforward view of all filesystems that are currently active and mounted in the Linux environment. This command lists the device names, mount points, filesystem types, and options, giving a comprehensive overview of the mounted filesystems.

Using the 'cat /proc/filesystems' command will not demonstrate the currently mounted filesystems. Instead, it displays the filesystems that the Linux kernel currently supports, which is quite different from what is being asked.

While 'lsmounts' is not a standard Linux command and 'free' is used to display memory usage, they do not pertain to the task of listing mounted filesystems. The 'mount' command is the most appropriate and widely used method for this purpose and therefore is the correct answer.