What colors are runway mandatory signs?

Answer: C — Red with White letters

Runway mandatory signs are designed to convey important operational information to pilots and vehicle operators, ensuring safety on the airfield. They are universally recognized by their red background and white lettering, which makes them highly visible and distinct from other signs on the airfield. The red color of these signs indicates that the message is critical and requires immediate attention, as they often denote instructions that must be followed, such as holding position or other mandatory actions related to runways and taxiways. The combination of red and white is standard across aviation to establish a clear and consistent understanding of these mandatory instructions, playing a crucial role in flight safety and effective airfield operations.