This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Oesophagus, Subject name: Surgery
Nonprogressive contraction of esophagus are: 
Select and explain. 
A. Primary, B. Secondary, C. Tertiary, D. Quaternary
C: Tertiary
Answer: C: Tertiary 
Explanation: Ans. (c) TertiaryRef: Sabiston 19th Edition, Page 1019* Primary and secondary peristalsis are normal* Tertiary peristalsis is abnormal