What does the letter 'C' signify for parallel runways?

The letter 'C' signifies the term "Center runway" for parallel runways. In airport operations, runways are often labeled with letters to indicate their position relative to each other, especially when they are parallel. In this case, the center runway designation helps pilots and air traffic control quickly identify the specific runway being referenced when multiple parallel runways are in use. This labeling system is crucial for maintaining safety and efficiency in air traffic management.

Contextually, runways are designated based on their spatial arrangement, and understanding these designations helps ensure that pilots can navigate the airfield safely and that air traffic controllers can provide clear instructions. The other terms provided do not accurately describe the specific designation related to parallel runways, which is why the center runway label correctly represents this context.