What generally distinguishes Class 5 hazardous materials (oxidizers and organic peroxides) from other classes in terms of their hazard?

Correct answer to question 135 (Hazardous Materials): They can intensify a fire by providing oxygen or reacting strongly with other materials, even if not flammable themselves

Why

Oxidizers and organic peroxides in Class 5 can intensify or sustain a fire by providing oxygen or reacting vigorously with other materials, even though they may not be flammable in the way a fuel would be.