What is required to ensure bicycle safety in Arizona?

The correct choice emphasizes the importance of both helmet use and adherence to traffic rules for bicycle safety in Arizona. Wearing a helmet is crucial as it significantly reduces the risk of head injuries during accidents. Additionally, following traffic rules ensures that cyclists are aware of their surroundings, have predictability in their movements for other roadway users, and can navigate streets safely. Traffic laws promote safe interactions between bicycles and motor vehicles, which is critical for preventing collisions.

The other options do not adequately promote bicycle safety. For instance, riding on sidewalks may not always be permissible and can pose risks to pedestrians. Riding without lights after dark increases the danger of being unseen by drivers, and limiting rides to only daylight hours does not address safety measures for when riding in low light conditions, which can happen at dusk or dawn.