When should drivers of charter buses allow riders on the bus?

The option indicating that riders should be allowed on the bus at departure time is appropriate because this approach aligns with the operational protocols for charter buses. Charter bus services are typically arranged for a specific departure time, and allowing passengers on at this moment ensures that the boarding process is well-coordinated and that the bus can leave as scheduled.

Waiting until departure time keeps the process organized, as it helps to minimize delays associated with boarding, such as managing the baggage loading or accommodating late arrivals. Timeliness is crucial in charter services, as it often influences the entire itinerary, which may include multiple stops or connections.

While it is important for baggage to be loaded and passengers to be accounted for before leaving, boarding at departure time is a practical measure that can ensure efficiency and respect the commitments made for service. Other options suggest various considerations, but none align with the ideal operational timing of allowing passengers to board the bus.