Take a snapshot first: task 2 and task 3 go through the boot loader. On the RHEL family the lab adds quiet to every kernel's command line if it isn't there, so that task 3 has something to remove. On Ubuntu it makes sure loglevel=7 isn't set. Reset puts the boot loader settings back as they were.

Tasks

Find out how this system booted. Write UEFI or BIOS on the first line of /root/lab-answers/1, and the default systemd target (such as multi-user.target) on the second.
Boot once into rescue mode from the boot loader menu, log in as root, run systemctl list-units --state=running, then systemctl reboot. Not graded: check yourself that only a handful of units were running. Root needs a password for rescue mode (passwd root); lock it again afterward with passwd -l root.
Make a lasting change to the kernel command line, then reboot. RHEL family: remove quiet from every installed kernel with grubby. Ubuntu: add loglevel=7 to GRUB_CMDLINE_LINUX_DEFAULT and run update-grub. Check /proc/cmdline after the reboot. Leave the change in place until you've run le-lab check; reset puts it back.

Hints

/sys/firmware/efi exists only on UEFI systems; systemctl get-default.
In the GRUB menu, e edits an entry: add systemd.unit=rescue.target to the end of the linux line and press Ctrl+x. Press Esc or hold Shift if the menu is hidden.
grubby --update-kernel=ALL --remove-args=..., grubby --info=ALL.
On Ubuntu, files in /etc/default/grub.d/ are read after /etc/default/grub and can set the same variable; cloud images set GRUB_CMDLINE_LINUX_DEFAULT in 50-cloudimg-settings.cfg.