What does a yellow airfield sign indicate?

Answer: B — Advisory information

A yellow airfield sign indicates advisory information. These signs are designed to provide pilots and ground personnel with guidance that is important for safe operations but does not dictate mandatory actions. For instance, they may indicate the location of runways, taxiways, and other features, thereby enhancing situational awareness for those navigating the airfield. In contrast, signs that convey mandatory instructions, such as those requiring immediate compliance from aircraft, are typically marked in red. Caution or warning signs might use other color conventions to alert personnel to specific hazards or conditions requiring attention. Directional signs that guide traffic toward terminals or other areas are usually green to signify guidance to a destination. By understanding the color coding and purpose of airfield signs, personnel can maintain safety and efficiency while driving on the airfield.