Explanation:

- Liver

- The liver is often called the 'chemical factory' of the body.

- It performs numerous chemical processes, including detoxification, protein synthesis, and production of biochemicals necessary for digestion.

- It plays a central role in regulating blood composition, including sugar, protein, and fat levels.

- Correct Answer

- Stomach

- The stomach is primarily involved in the digestion of food.

- It uses acid and enzymes to break down food, but it's not primarily a chemical factory like the liver.

- Kidneys

- Kidneys filter blood to remove waste and maintain a balance of salts and minerals.

- They are more a filtering system than a chemical factory.

- Lungs

- The lungs are responsible for gas exchange, taking in oxygen and expelling carbon dioxide.

- They do not perform complex chemical processes like the liver.