Which of the following best describes flammable solids?

• A. Only liquids that burn slowly.
• B. Explosives that are dry.
• C. Any material except explosives that can be readily ignited and will burn intensely and persistently and cause a transportation hazard.
• D. Any solid that cannot ignite.

Answer: (C)

Flammable solids are materials that can ignite readily and burn vigorously, continuing to burn and creating a hazard in transport. The description that fits this best identifies a material (not an explosive) that can be readily ignited, will burn intensely and persistently, and poses a transportation hazard. This captures the essential idea: solids that ignite easily and sustain a strong flame, unlike substances that cannot ignite or that are simply explosives. The other choices misstate the nature of flammable solids—one describes liquids, another focuses on explosives, and the last describes solids that cannot ignite.