Final answer:
Passing is prohibited on the shoulder of the road as it is unsafe and not designated for regular vehicle travel.
Step-by-step explanation:
Passing is prohibited on the shoulder of the road. This is because the shoulder is not designed for normal vehicle travel and is typically reserved for emergencies, breakdowns, or for law enforcement use. It can be dangerous to pass on the shoulder due to debris, uneven road surfaces, and it may be illegal in many jurisdictions. While the other options may have specific rules or context that might affect when passing is allowed or not (e.g., passing in a school zone during certain hours), the shoulder of the road is broadly considered an area where passing is not permitted.