Which fire extinguisher agent is often used for controlling flammable liquids?

The correct agent for controlling flammable liquids is foam. Foam extinguishers work by creating a blanket of foam that suffocates the fire while also preventing the release of flammable vapors from the liquid. This is particularly effective for Class B fires, which involve flammable liquids like gasoline, oil, and solvents. The foam cools the burning surface and forms a barrier between the liquid and the oxygen in the air, which helps to suppress the fire.

While dry chemical agents are also effective against flammable liquids, they operate differently and may leave a residue that requires additional cleanup. Water, on the other hand, is not suitable for flammable liquid fires as it can spread the flames by causing the burning liquid to splash. Carbon dioxide extinguishers can be used for flammable liquids but are generally not as effective as foam when it comes to covering larger surface areas of burning liquid and preventing re-ignition. Thus, foam stands out as the most suitable option for this specific scenario.