What must a pilot-in-command do when their aircraft is in flight or maneuvering on the surface?

The correct answer is that a pilot-in-command must give way to an aircraft that is landing or about to land. This is rooted in the principle of hierarchy in aviation regulations to prevent collisions and maintain safe operations around airports. When approaching to land, an aircraft typically has the right-of-way because it is in a critical phase of flight, and allowing it to land safely is essential for orderly air traffic management.

In most aviation systems, especially during the landing approach, an aircraft is maneuvering at slower speeds and often has less maneuverability compared to other aircraft that may be still climbing or cruising. Therefore, it's crucial for pilots to yield to landing aircraft as part of their responsibilities to ensure safety in congested airspace.

While maintaining a safe distance and altitude with respect to other aircraft is necessary, giving way to landing aircraft takes precedence. The other options involve actions that could potentially lead to collisions or unsafe situations if not executed appropriately in relation to the right-of-way rules. Thus, recognizing the critical importance of the landing process in aviation operations is why yielding to an aircraft that is landing or about to land is essential for pilots-in-command.