What is a through flight?

A through flight refers to a flight that involves one or more intermediate stops but operates under a single flight number and itinerary. This means that passengers do not need to check in again when transferring to the next leg of their journey, making it a smoother travel experience.

In the context of the definitions provided, while option A describes a nonstop flight connecting two airports without land stops, it does not align with the concept of a through flight. Option B talks about a direct flight without delays, which again does not capture the essence of what a through flight is, as it may involve delays at the intermediate stops. Option D mentions a round trip, which is unrelated to the concept of a through flight that can involve different locations and requires the specific characteristic of intermediate stops.

Thus, the understanding of a through flight primarily hinges on its nature of including stops while maintaining a single journey ticket, making the choice that correctly characterizes this concept appropriate.