What color is the NBC marking sign for gas?

The NBC (Nuclear, Biological, and Chemical) marking sign for gas is recognized by its specific color scheme. The correct answer indicating that the sign is yellow with red lettering aligns with standardized military markings that ensure clear communication and visibility. Yellow is often associated with caution and danger, making it an appropriate choice for indicating the presence of hazardous substances. The red lettering serves as a warning, capturing attention and indicating that immediate action or caution is necessary due to the potential threat posed by NBC substances. This distinctive color combination is crucial for the effective identification and response to NBC threats in a combat environment.