Concept:Sodium chloride is not used directly to treat or disinfect drinking water.Explanation:NaCl is used to manufacture chlorine gas, Cl2, through electrolysis. It is also widely used as a food preservative to prevent spoilage. In soap production, NaCl is added to separate soap from glycerol by a process called salting out. However, water treatment typically uses chlorine gas, Cl2, and not sodium chloride itself.Answer:A. treatment of water