Which of the following is a hazard class you must avoid smoking around?

The correct choice is oxidizers because they have the potential to cause or enhance the combustion of materials. Oxidizers can react violently with flammable substances, increasing the risk of fire or explosion, especially when exposed to heat or open flames, such as from smoking. When working with or near oxidizers, it is crucial to maintain a safe environment by eliminating sources of ignition to prevent dangerous reactions.

Understanding the nature of other hazard classes is also important. Corrosives can cause destruction of living tissue and severe corrosion on materials, but they do not inherently pose a fire risk the way oxidizers do. Environmental hazards primarily deal with substances that may cause environmental damage but don't typically pose immediate fire hazards. Radioactive materials present health risks through radiation exposure, but their association with combustion or fire in the context of smoking is less direct compared to oxidizers.