A/an ____________ may readily react to promote or initiate combustion of combustible materials.

• A. Combustible material
• B. Oxidizer
• C. Flammable gas
• D. Pyrophoric material

Answer: (B)

Oxidizers are substances that readily provide oxygen or another oxidizing agent to support combustion. They don’t have to burn themselves; their key hazard is that they promote or initiate burning of fuels by supplying the oxygen needed for the fire to start or intensify, often releasing heat in the process. This makes them the best fit for “may readily react to promote or initiate combustion of combustible materials.”

A combustible material and a flammable gas are fuels themselves—they contribute to burning when an oxidizer is present, but they don’t act as the agent that promotes combustion. A pyrophoric material can ignite spontaneously in air, which is a different behavior (spontaneous ignition) and not the general mechanism of promoting combustion by providing an oxidizing agent.