What encompasses all portions of a passenger's journey from beginning to end, even if separated by gaps?

The correct choice encompasses all portions of a passenger's journey from beginning to end, even if there are gaps in the travel. An itinerary, in this context, refers to the detailed schedule that outlines the various segments of travel, including flights, layovers, and any other relevant travel arrangements. It serves as a comprehensive overview of the entire journey, ensuring that the traveler knows what to expect throughout their trip.

An itinerary can include different modes of transportation, accommodations, and activities planned during the journey, thus giving a clear picture of the passenger's travel experience. This is crucial for both the traveler's planning and for service providers in managing passenger needs throughout the journey.

The other options, while related to travel, do not capture the full scope of a passenger's journey. A flight refers specifically to the airborne segment between two points. Baggage pertains to the passenger's luggage rather than their overall travel experience. The role of a purser relates to an airline staff position and does not represent the journey of the passenger as a whole. Therefore, the itinerary is the most encompassing term reflecting the entire travel experience from start to finish.