What should you do when you encounter a roundabout?

When you encounter a roundabout, the correct action is to yield to traffic that is already circulating in the roundabout before you enter. This is crucial because vehicles within the roundabout have the right of way, and yielding helps maintain a smooth flow of traffic, reducing the risk of collisions.

Entering the roundabout without giving way can create confusion and lead to accidents, as vehicles will not be expecting an entering vehicle. By yielding, you ensure that you merge safely with the ongoing traffic, contributing to the overall efficiency and safety of the roundabout system.

The other options present actions that either go against traffic regulations or do not help in safely navigating a roundabout. Stopping might cause unnecessary delays and is typically not advised unless absolutely necessary, while accelerating to merge can create dangerous situations. Making a U-turn to avoid the roundabout is generally not an appropriate response and typically violates driving laws regarding roundabout usage.