Answer: Option (4) is the correct answer.
Step-by-step explanation:
A process in which a fat or oil is converted into soap and alcohol with the help of heating in the presence of aqueous alkali is known as saponification.
When an acid is heated with alcohol then it results in the formation of an ester. This process is known as esterification.
When number of monomer units in a chemical reaction react together to result in the formation of a polymer then the process is known as polymerization.
When a substance dissociates or breaks into simpler substances by the action of bacteria then this process is known as fermentation. Organisms like yeast, bacteria etc helps in the process of fermentation.
Thus, we can conclude that saponification is the reaction which results in the production of soap.