Explanation:

- Sodium stearate, sodium palmate, and sodium oleate are all types of soaps. They are salts of fatty acids, commonly used in soap formulation because they emulsify and dissolve oils and dirt, allowing them to be washed away with water.

- Sodium benzoate is not a soap; it is a preservative commonly used in foods, beverages, and toiletries to prevent microbial growth and spoilage.

Answer: Option 3 - Sodium benzoate