Which of the following is not a hazard symbol pictogram?

The question seeks to identify which option does not represent a recognized hazard symbol pictogram. The correct choice is the question mark.

Hazard symbols, or pictograms, are specific images designed to convey information about the type of hazards present, ensuring that individuals can understand risks at a glance. The flame pictogram indicates a flammable substance, the skull and crossbones represents toxicity or lethal hazards, and the exclamation mark signifies a general hazard that may cause irritation or other health effects.

In contrast, the question mark is not a recognized hazard symbol pictogram. It does not convey a specific risk or hazard type as the others do. Its use in safety contexts usually indicates uncertainty or requires further clarification, rather than indicating a specific safety concern related to hazardous materials.