What light should be used during the day for increased visibility?

Answer: C — High beam or daytime running lights

Using high beam or daytime running lights during the day significantly enhances visibility for motorcyclists. This practice makes motorcycles more noticeable to other road users, especially in bright sunlight or varying weather conditions. Daytime running lights are specifically designed to be used during daylight hours, providing a continuous light that increases the visibility of the motorcycle without blinding oncoming drivers. High beam lights can also be effective during the day but should be used according to the riding environment to avoid dazzling other drivers. In contrast, parking lights are generally not intended for use while in motion, as they do not provide sufficient illumination to ensure visibility. Fog lights are designed to help see better during bad weather but are not intended for daytime use or to increase visibility in normal conditions. Therefore, the option of using high beam or daytime running lights is the best choice to ensure that the motorcycle stands out on the road in daylight.