What does a roundabout sign instruct drivers to do?

Answer: B — Reduce speed and yield to pedestrians and vehicles already in the circle

A roundabout sign instructs drivers to reduce speed and yield to pedestrians and vehicles already in the circle because roundabouts are designed to improve traffic flow and enhance safety. When approaching a roundabout, drivers should slow down to assess the traffic conditions. Yielding is essential to allow vehicles and pedestrians already in the roundabout the right of way. This approach helps prevent congestion and reduces the chances of accidents, as vehicles can continue moving while entering and exiting the roundabout without the delay of a stop sign or traffic signal. It’s also crucial for drivers to remain attentive to pedestrians, as they often have crossing points marked around the roundabout. In contrast to this correct answer, increasing speed to merge quickly would be unsafe and contrary to the intended function of roundabouts. Stopping completely before entering would disrupt the flow of traffic; instead, yielding is the appropriate action. Making a U-turn is not relevant, as roundabouts are designed to facilitate smooth navigation without the need for such maneuvers.