Solution:Concept- The water-based, or aqueous, solution of hydrogen chloride gas is known as hydrochloric acid. It is also the primary ingredient in gastric acid, which is naturally generated in the human stomach to aid with food digestion.
Hydrochloric acid is produced in the stomach, which helps in maintaining the pH of the stomach. HCl helps in making the acidic environment in the stomach which helps the enzymes to work efficiently. Some enzymes like pepsin work in acidic pH, which does the metabolic activity.
Hence, the correct answer is option (3).