Which one of the following is used as preservative?

Sodium benzoate is commonly used as a food preservative. It inhibits the growth of bacteria, yeast, and fungi in acidic foods and beverages, extending their shelf life. While sodium chloride (common salt) is also a preservative, sodium benzoate is more specifically used as a chemical preservative in processed foods. Copper sulphate is used as a fungicide, and ammonium sulphate is primarily a fertilizer.