What does "deadheading" imply in the context of crew travel?

"Deadheading" refers specifically to the practice of airline crew members traveling as passengers on a flight in order to reposition themselves for their next assignment. This often occurs when crew members need to travel from one location to another, typically to meet a scheduled flight or to return to their home base after completing their duty. This process ensures that the necessary flight crew is present for upcoming flights, maintaining operational efficiency.

In the context of the provided choices, the aspect of deadheading that involves crew members traveling between two flights on duty accurately captures the essence of this term, which is critical for managing flight operations and ensuring the crew is available where they are needed most.