Which of these options is NOT an effective way to improve visibility while riding?

Improving visibility while riding is crucial for safety, and the option of driving without lights during the day does not contribute to this goal. In fact, riding without lights significantly reduces a rider's visibility to other vehicles and pedestrians, increasing the risk of accidents.

In contrast, wearing reflective clothing enhances a rider's visibility by making them more noticeable to drivers, especially in low-light conditions. Using turn signals is essential for signaling intentions to other road users, thereby preventing miscommunication and potential collisions during lane changes. Maintaining a safe following distance is another key factor; it allows for appropriate reaction time to any hazards or changes in traffic conditions, ensuring that the rider can stop or maneuver safely if needed.

Therefore, the option of driving without lights is clearly not an effective method for improving visibility and is detrimental to a rider's safety on the road.