True or False: High-expansion foams can be used on either Class A or Class B fires.

High-expansion foams are designed to expand significantly in volume and can effectively cover large areas, making them versatile for different fire types. They are primarily used for suppressing Class B fires, which involve flammable liquids, but they can also be applied to Class A fires, which involve ordinary combustible materials like wood, paper, and textiles.

The ability of high-expansion foams to blanket the fuel source helps to smother the fire, reduce heat, and prevent re-ignition, thus applying their effectiveness to both classes of fires. This quality differentiates high-expansion foam from other forms of fire suppression materials that may be limited to one specific class.

In summary, high-expansion foams can be used on both Class A and Class B fires, confirming that the statement is true.