What are some types of vehicles authorized to operate on the airside?

The correct choice identifies service vehicles, maintenance vehicles, and aircraft push-back tugs as authorized to operate on the airside. This option encompasses essential vehicles that are integral to airport operations. Service vehicles are crucial for providing assistance to aircraft, while maintenance vehicles ensure that the infrastructure and systems at the airport remain functional and safe. Aircraft push-back tugs specifically assist in maneuvering aircraft away from gates safely, which is vital for maintaining the flow of air traffic and preventing potential accidents on the airside.

The other options do not fully meet the criteria for authorized vehicles. While passenger vans can be authorized for specific purposes, they do not represent the primary types of vehicles that operate in the critical areas of the airside. Maintenance vehicles are indeed authorized, but limiting the answer solely to maintenance vehicles overlooks the wide variety of other necessary service vehicles. Lastly, private vehicles are generally not allowed on the airside due to safety and security protocols, which is why that response does not align with operational standards at an airport.