Under what conditions must a red reflector be visible from the rear of a bike?

A red reflector must be visible from the rear of a bike from a distance of 50-300 feet to meet safety standards. This requirement ensures that the bike is clearly seen by drivers and other road users from a sufficient distance, especially during low visibility conditions such as at dusk, nighttime, or in inclement weather.

The visibility range is determined to provide adequate warning to approaching vehicles, allowing them enough time to react and maintain a safe distance from the cyclist. This distance, set between 50 to 300 feet, balances practicality and safety by ensuring that the reflector is effective across various conditions on the road.

While the other options suggest different distances, they do not align with the established safety regulations. The range of 50-300 feet is specifically designed to provide optimal visibility without being excessive, which could lead to misunderstandings about the appropriate distance for visibility and safety.