When passing in the same direction, when must drivers return to the right?

Answer: C — As soon as it is safe to do so

Drivers must return to the right as soon as it is safe to do so after completing a pass. This guideline ensures that drivers do not remain in the left lane longer than necessary, which can create hazards for other vehicles trying to pass or maintain their speed. Returning to the right promptly helps maintain smooth traffic flow and minimizes the risk of accidents. The phrase "as soon as it is safe" emphasizes the importance of gauging the surrounding traffic conditions and ensuring there is enough space before making the lane change. This requires drivers to be aware of their surroundings, including the speed and proximity of vehicles behind them, to avoid putting themselves or others in danger during the maneuver. In this context, simply returning as soon as possible without regard for safety could lead to dangerous situations, such as cutting off other vehicles. Waiting until fully passing might not consider the need for efficient traffic flow, and signaling after completing a pass doesn't account for safety before executing the maneuver. Thus, the correct approach prioritizes careful assessment and safety when returning to the right lane.