Final answer:
Drivers must dim high beams or low beams with fog lights when within 500 feet of an oncoming vehicle to avoid glare and promote safety.
Step-by-step explanation:
If you are driving with your high beam lights on or your low beam lights with fog lights on, you must dim them before coming within 500 feet of any oncoming vehicle so the oncoming driver is not blinded by the glare. The correct answer to the question is D) 500 feet.
This is a rule that could vary slightly depending on the jurisdiction, but the general practice is cited for safety reasons and to prevent accidents due to glare.