When is it illegal to pass a vehicle?

Passing a vehicle is illegal in certain situations that pose safety risks to drivers and pedestrians. The correct option highlights that it is illegal to pass at intersections, on hills, and on curves. This is primarily due to visibility issues and the increased likelihood of encountering oncoming traffic or obstacles that can lead to accidents.

At intersections, visibility may be limited, and vehicles may be making turns or stopping unexpectedly. On hills and curves, the road layout can prevent drivers from seeing oncoming traffic or cyclists, thus creating a dangerous situation if a driver attempts to pass. These areas are typically marked with signs indicating no passing zones, reinforcing the importance of maintaining safety in these potentially hazardous locations.

The other scenarios mentioned in passing restrictions, such as residential streets, school zones, and one-way streets, may have specific rules but do not universally prohibit passing in the same manner that intersections, hills, and curves do, where visibility and safety are greatly compromised. Hence, focusing on the critical aspects of road safety, especially in critical situations, justifies why passing is illegal in those specified areas.