What must a truck driver verify regarding the fifth-wheel lock before departing with a semi-trailer?

1. That the kingpin is fully engaged in the locking jaws, the safety latch is locked, and there is no gap between the fifth wheel plate and trailer apron
2. That the coupling is completely loose so it can rattle freely
3. That the landing gear is firmly resting on the asphalt while driving
4. That the trailer brake lines are disconnected