What should a driver do to prepare for entering a roundabout?

Answer: B — Yield to vehicles already in the roundabout

To prepare for entering a roundabout, the correct action is to yield to vehicles that are already circulating within the roundabout. This ensures a smooth flow of traffic and helps prevent accidents, as vehicles already in the roundabout have the right of way. By yielding, a driver can gauge the traffic conditions and safely enter the roundabout when there is a sufficient gap. Other options do not align with safe practices when approaching a roundabout. Accelerating before entering can create conflicts with ongoing traffic and lead to dangerous situations. Signaling right immediately might mislead other drivers about your intentions, as it is not the typical maneuver when preparing to enter. Additionally, stopping in the middle of the intersection can cause confusion and disrupt the flow of traffic, making it hazardous for both the driver and other road users.