Hazmat division 5.1 hazards are described as...

• A. Generally by yielding oxygen can cause or enhance combustion
• B. Organic Peroxides containing oxygen
• C. They produce toxic fumes
• D. They are non-reactive with water

Answer: (A)

Division 5.1 hazards are oxidizers: substances that release oxygen or provide an oxygen source during a chemical reaction. That oxygen can cause fires to start more easily and burn more vigorously, even with a heat source that wouldn’t normally ignite the material. So the defining feature is their ability to yield oxygen and thereby support or accelerate combustion of other materials.

This is why the statement describing them as generally by yielding oxygen that can cause or enhance combustion is the best fit. Organic peroxides, which do contain oxygen, belong to a different category (5.2) with their own distinct properties. The idea that these hazards inherently produce toxic fumes isn’t a defining trait of all 5.1 oxidizers, and saying they are non-reactive with water is incorrect, since many oxidizers can react with water or release heat when in contact with moisture.