Peristalsis is the involuntary movement of the longitudinal and circular muscles, primarily in the digestive tract. It occurs as progressive wave-like contractions. Peristaltic waves occur in the oesophagus, stomach, and intestines. In the oesophagus, peristaltic waves begin at the upper portion of the tube and travel the whole length, pushing food ahead of the wave into the stomach. Thus, the correct answer is option C.