What must a driver do when approaching a roundabout?

Answer: A — Yield to traffic already in the roundabout.

When approaching a roundabout, a driver must yield to traffic that is already in the roundabout. This is crucial because vehicles circulating within the roundabout have the right of way. Yielding allows for a smooth flow of traffic and helps prevent collisions at this point of intersection. By yielding, drivers ensure that they can enter the roundabout only when it is safe to do so, allowing them to merge into the flow of traffic without hindrance. Understanding this helps promote safer driving habits, as it reduces the likelihood of accidents that can occur when drivers attempt to force their way into the roundabout without yielding properly. Other options may not be advisable as they can create unsafe situations. Accelerating quickly to enter the roundabout is typically unnecessary and could lead to conflicts with vehicles already driving in the roundabout. Coming to a complete stop before entering might disrupt the flow of traffic and could lead to rear-end collisions, especially if the driver behind is not expecting a stop. Turning on headlights, while generally safe practice in low visibility conditions, isn't a requirement specifically when approaching a roundabout.