Which of the following is NOT a category of hazardous materials?

Non-reactive materials are considered the correct choice for the category that is not classified as hazardous materials.

Hazardous materials are typically categorized based on their potential risks and dangers they pose to health and safety. Compressed materials, corrosive materials, and flammable materials all present specific hazards, such as the potential to explode, damage living tissues, or ignite easily, respectively.

On the other hand, non-reactive materials do not have harmful chemical interactions and do not pose a threat to safety in the same way. They are often stable and do not contribute to hazards that would require specialized handling or storage protocols defined for hazardous materials. Thus, understanding these distinctions is crucial when working with or around various materials to ensure safety and compliance with regulations.