What percentage of light must come through the windshield?

Answer: C — 70%

The correct percentage of light that must come through the windshield is 70%. This requirement ensures that drivers have adequate visibility while operating a vehicle, which is crucial for safety on the road. By having at least 70% of light transmission, it helps to reduce glare and allows the driver to see clearly in various lighting conditions. This regulation applies specifically to windshield materials to ensure they provide enough transparency to maintain visibility standards. Options may vary, but for windshields, they are designed to maintain high transparency to ensure that drivers can see road signs, other vehicles, and any obstacles effectively, which is essential for safe driving. Lower percentages of light transmission would create potential hazards and increase the risk of accidents, as drivers might struggle to see clearly.