What of the following statements are true regarding /dev/ when using udev?

Entries for all possible devices get created on boot even if those devices are not connected.

Additional rules for udev can be created by adding them to /etc/udev/rules.d/.

When using udev, it is not possible to create block orcharacter devices in /dev/ using mknod.

The /dev/ directory is a filesystem of type tmpfs and is mounted by udev during system startup.

The content of /dev/ is stored in /etc/udev/dev and is restored during system startup.