When is it appropriate to use high beams?

Answer: C — On dark roads with no oncoming traffic

Using high beams is appropriate on dark roads with no oncoming traffic because they provide increased visibility by illuminating a wider area ahead. This is particularly beneficial in rural areas or roads without street lighting, where regular headlights may not be sufficient to see obstacles, pedestrians, or wildlife. High beams can help drivers see further down the road, allowing for reaction time to any potential hazards. During daytime driving, high beams are unnecessary and can cause glare for other drivers, making option A unwise. In areas with street lighting, there is typically enough illumination for safety, making high beams redundant, which relates to option B. While high beams can be advantageous on highways due to higher speeds and more distance visibility, they are not exclusively designated for highway use, ruling out option D. Hence, option C is the most appropriate and responsible usage of high beams.