Under what circumstance may an operator legally pass to the right of another vehicle?

The correct answer centers on the condition that safe passing must always be ensured. According to traffic laws and safety protocols, an operator may legally pass to the right of another vehicle when it is safe to do so. This means that the operator has a clear view that allows them to make a safe maneuver, which includes an assessment of traffic, road conditions, and the behavior of other vehicles.

Passing to the right can occur in situations such as when the vehicle being passed is turning left or is in a designated lane that allows for such a maneuver. The emphasis on safety implies that conditions must be favorable, ensuring that there is no risk of collision or danger to others on the road.

In contrast, the other options do not encompass the broader principle of safety. Passing when a vehicle is stationary may not always be an option due to the potential for sudden movement or other vehicles in the vicinity. Low visibility conditions do not inherently provide safe passing opportunities; these conditions often require increased caution. Similarly, passing only when the road is clear overlooks the necessity of considering other factors such as the speed and presence of oncoming traffic, which may impede a safe passing scenario.