Explanation:

- Option 1: Acetic acid is commonly found in vinegar but is not produced in the stomach.

- Option 2: Nitric acid is a strong acid used in industrial processes, not in the human body.

- Option 3: Citric acid is found in citrus fruits and is not produced by the gastric glands.

- Option 4: Hydrochloric acid is indeed the acid produced by gastric glands in the stomach. It aids in digestion and protects against pathogens.