What does a white painted 'X' on a runway indicate?

Answer: C — The runway is closed to all aircraft operations

A white painted 'X' on a runway serves a critical purpose in airfield operations. It indicates that the runway is closed to all aircraft operations. This marking is prominently displayed to ensure that pilots and ground personnel are aware that the runway cannot be used for takeoffs, landings, or any other operations. The 'X' acts as a clear and unambiguous signal, preventing any potential confusion that could arise if an aircraft attempted to use that runway. In contrast, markings or signs indicating that a runway is open or available for other types of operations would not feature a white 'X.' Those roles are signified with different colors and symbols, ensuring that air traffic maintains safety and operational efficiency. Therefore, the presence of the 'X' is a critical safety feature to alert everyone involved of the runway's status.