Which of the following is NOT a common dry chemical agent?

The choice selected is considered correct because sodium chloride, while often used in other contexts such as food preservation, does not function as a common dry chemical agent for fire suppression. Instead, sodium bicarbonate, potassium bicarbonate, and monoammonium phosphate are all recognized for their effectiveness in extinguishing certain types of fires, particularly those involving flammable liquids and combustible materials. These specific agents are utilized due to their specific chemical compositions that work effectively to interrupt the combustion process.

Sodium bicarbonate and potassium bicarbonate release carbon dioxide when heated, which helps to smother flames. Monoammonium phosphate serves as a versatile dry chemical extinguisher, effective on a wide variety of fires. In contrast, sodium chloride is not typically used in the context of fire extinguishing agents, making it the exception among the listed choices.