Question

to avoid getting rear-ended.by another vehicle in an emergency, you should: turn your head and look over your shoulder check your rearview mirror often start braking early as a signal to the driver behind yo drive with your left foot on the brake pedal at all times

Explanation:

To avoid being rear - ended in an emergency, starting to brake early signals the driver behind. Turning head/shoulder is for blind - spot checks, rearview mirror check is regular, and driving with left foot on brake is unsafe (right foot for brake in standard driving). So the correct action is to start braking early.

Answer:

Start braking early as a signal to the driver behind you (the third option: "Start braking early as a signal to the driver behind yo" - assuming "yo" is a typo for "you")