The rear fog light shall be used whenever...
A)driving at abnormally reduced speed.
B)driving on high mountain roads.
C)weather conditions are especially unfavorable.Correct
# Rear Fog Light
The rear fog light must be used **when there are especially unfavorable weather conditions**, such as dense fog, very heavy rain or snow. This light is intense red in color and is intended to make us visible to vehicles driving behind us in low visibility situations. It is not used simply because of driving slowly or being in the mountains, but specifically when weather conditions require it for road safety.