Final answer:
Foam is the extinguishing agent that interrupts combustion, largely due to its ability to reduce water's surface tension with surfactants, allowing it to spread over and extinguish fires involving organic liquids.
Step-by-step explanation:
Extinguishing agents such as foam interrupt or inhibit the combustion reaction and stop chemical flame production. Foam is effective because it is an aqueous solution of fluorinated surfactants that reduce the surface tension of water below that of fuel. This allows the foam to spread across the burning surface, thereby extinguishing the fire. This is based on the principle that soaps and detergents, also known as surface-active agents or surfactants, disrupt the intermolecular attractions between water molecules, which results in reduced surface tension. In the 1960s, US Navy researchers developed foams specifically to fight fires aboard aircraft carriers and these fluorinated solutions are now globally used to combat large-scale fires involving organic liquids.