The correct option is
B Alimentary canal
The process of peristalsis begins in the oesophagus when a bolus of food is swallowed. The strong wave-like motions of the smooth muscles in the oesophagus carry the food to the stomach, where it is churned into a liquid mixture called chyme. The movement of food in the alimentary canal occurs through peristalsis.
Hence the correct answer is (D)