Which of the following is a location where passengers are not allowed to ride?

Passengers are prohibited from riding in any trailer, cart, or igloo because these vehicles are designed specifically for equipment transportation, baggage handling, or other operational purposes, rather than for passenger transport. The design and function of these vehicles do not ensure safety or comfort for passengers, and allowing passengers to ride in them could create hazardous situations for both the occupants and operational efficiency.

In contrast, designated waiting areas, shuttle buses, and service vehicles are all established with the intention of accommodating passengers safely and efficiently. Designated waiting areas provide a structured place for passengers to gather before boarding, while shuttle buses are specifically designed to transport passengers around the airport. Service vehicles typically comply with safety regulations that allow for passenger transport under certain conditions.