Substances classified as ORM-D fall under which category?

The classification of ORM-D, which stands for "Other Regulated Materials," is specifically designed for materials that are not covered under other more stringent regulations for hazardous materials but still require some level of regulatory oversight during transport. These materials can often be transported with fewer restrictions than more hazardous substances, making them important for certain consumer goods and everyday products.

ORM-D items typically include items that pose minimal hazards during transport, such as limited quantities of certain flammable liquids, batteries containing small amounts of corrosive materials, and personal care products containing restricted substances in defined amounts. This classification allows for the safe transport of these materials while acknowledging their potential risk without imposing the full burden of hazardous materials regulation.

The other options pertain to specific types of hazardous materials that have more severe implications. Extremely toxic substances, corrosive liquids, and flammable materials are all subject to stricter regulations than those classified as ORM-D, which reflects their potential danger to public safety and environmental health. Therefore, the correct classification of ORM-D as "Other Regulated Materials" emphasizes its distinctive position in the hierarchy of hazardous materials transport regulations.