In the NFPA 704 System of Identification, what colour is the diamond-shaped placard used to indicate a fire hazard?

Answer: C — Red.

In the NFPA 704 System of Identification, the diamond-shaped placard that indicates a fire hazard is colored red. This color coding is part of a standardized system used to quickly convey information about the hazards associated with materials in use or storage. The red section of the placard clearly communicates the degree of flammability of the substance. It uses a numerical scale from 0 to 4, with 0 indicating that the material poses minimal or no fire hazard, and 4 indicating that it is extremely flammable, capable of ignition under almost all conditions. Thus, the red color serves as a visual alert to responders about the potential fire risks associated with the substance, enabling them to take appropriate safety measures.