Which situation is ideal for overtaking and passing another vehicle on the right?

Overtaking and passing another vehicle on the right is often considered safe and appropriate in a situation where the vehicle ahead is making or about to make a left turn. This is because the vehicle making a left turn is likely to move toward the left side of the road, which opens up space on the right for another vehicle to safely pass. It's crucial in this case that the driver passing on the right ensures there is sufficient room and that it is safe to do so, as left-turning vehicles may not always check their right flank.

In contrast, the other scenarios may not provide the same safety or legality for passing on the right. For example, passing in a designated passing zone typically refers to situations on the left where overtaking is clearly permissible. A clear road is ideal for general driving but does not specifically relate to the action of passing on the right—it doesn't guarantee that other vehicles won't introduce danger. Attempting to pass at a red light could result in running a red signal, which is illegal and creates a hazard. Thus, the situation concerning a vehicle turning left is specifically advantageous for executing a right-side pass when done with caution.