What hazard may be indicated by the symbol of a flame inside a circle?

The symbol of a flame inside a circle specifically indicates the hazard associated with oxidizers. Oxidizers are substances that can cause or enhance the combustion of other materials, meaning they can increase the fire risk when they come into contact with flammable materials or substances. The presence of the flame symbol reinforces the idea that the material poses a significant fire hazard due to its ability to act as an oxidizing agent, facilitating combustion.

In contrast, the other choices represent different hazards. Corrosives typically have a symbol indicating damage to living tissue or materials. Flammable liquids are designated with a flame symbol but do not include the circle, which is specifically reserved for oxidizing agents. Environmental hazards would be indicated by a different symbol, often depicting a dead fish or tree, highlighting their potential harm to ecosystems. Thus, the flame inside a circle is clearly representative of oxidizers, making this the correct interpretation of the symbol.