When arriving first at the scene of a traffic crash involving an unconscious motorcyclist lying on the pavement, what is the critical first-aid rule regarding their helmet?

1. Immediately pull the helmet off vigorously to check for facial cuts
2. Do NOT remove the helmet unless the airway is obstructed and you are a trained professional, as moving it can cause permanent spinal cord severance
3. Loosen the helmet and rotate the victim's head 180 degrees
4. Remove the helmet and place it under the victim's knees