Answer: D. esophagus
Explanation: Because esophagus uses muscles and does not use enzymes to digest. It only transports food to the stomach and then goes further into the digestive system.
Why not your mouth because it uses the enzyme Amylase, which helps break down complex carbohydrates. It is also produced by the mouth. Lipase, which breaks down fats. Protease is a protein-breaking enzyme that breaks down proteins.
Your stomach also uses enzymes as your intestine.
I hope I helped!