Which of the following materials is NOT a representative of Class D fires?

Class D fires are fires that involve combustible metals, which react with water and other substances in a highly exothermic manner. The representative materials commonly associated with Class D fires include magnesium, aluminum, and lithium.

Magnesium and aluminum are both lightweight metals that can ignite and burn fiercely when exposed to air, particularly in powder form. Lithium, another metal, can also create a Class D fire hazard due to its reactive properties.

On the other hand, petrol (gasoline) does not fall under the Class D category as it is a flammable liquid, which represents Class B fires. Class B fires typically involve fires caused by flammable liquids and gases. Therefore, identifying petrol as the material that does not represent Class D fires is correct since it belongs to a different class of fire hazards entirely.