When backing up your vehicle, you should:
Turn your head and body to the right to look out the rear window.
Use only your rearview mirror to look for obstacles to the rear of your vehicle.
Honk your horn so pedestrians and other vehicles know what you are doing.
None of these.
When backing, don’t depend on your mirrors. Instead, with your left hand at the top of the steering wheel, turn your head and body to the right and look out the rear window.