Final answer:
For fires involving ethanol, the most suitable choice is Alcohol-Resistant Aqueous Film-Forming Foam (AR-AFFF), which is designed to create a barrier to prevent the ethanol from breaking down the foam and enables effective fire suppression.
Step-by-step explanation:
When dealing with fires involving ethanol, which is a type of alcohol, it's important to use a firefighting foam that is designed to effectively combat this specific type of fire. The standard Aqueous Film-Forming Foam (AFFF) is not suitable for alcohol fires because ethanol can break down the aqueous film, rendering the foam ineffective. In contrast, Alcohol-Resistant Aqueous Film-Forming Foam (AR-AFFF) is designed with a polymer that forms a protective layer between the fuel and the foam, preventing the breakdown of the foam blanket.
This allows the AR-AFFF to suppress the fire more effectively. Other options, such as Protein Foam, Film-Forming Fluoroprotein Foam (FFFP), and High-Expansion Foam, are generally not as effective against polar solvents like alcohols. Hence, for fires where ethanol is the known material, the best choice among the options provided is B) Alcohol-Resistant Aqueous Film-Forming Foam (AR-AFFF).