Which of the following is NOT a type of special extinguishing agent?

Flammable liquids are substances that can ignite and burn easily, making them fuels rather than agents used for extinguishing fires. In the context of firefighting, special extinguishing agents are those specifically designed to suppress, control, or extinguish different types of fires effectively.

Wet chemicals are commonly used for kitchen fires, particularly those involving cooking oils and fats, as they can cool the flames and create a barrier between the fire and the air. Clean agents, which are typically non-conductive and leave no residue, are effective for electronic equipment and delicate items where water and other agents might cause damage. Dry chemicals are versatile and can be used on various types of fires; they interrupt the chemical reaction of the fire triangle.

In summary, while wet chemical, clean agent, and dry chemical are all specialized agents employed in extinguishing fires under specific conditions, flammable liquids do not fit this classification and represent a serious risk by contributing to fire rather than controlling it.