This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T, Subject name: Medicine
A 60-year old male pressents with progressivp difficulty in swallowing, vomiting and ocLsional regurgitation for the past 3 months. Barium studies showed marked dilatation of the upper esophagus with narrowmg of the lower segment. Manometry showed absent esophageal peristalsis. The pathogenesis of this condition is most likely related to- 
Select and explain. 
A. Reflux of gastric acid into the lower esophagus, B. Abnormal dilatation of lower esophageal vein, C. Incompetence of the lower esophageal sphincter, D. Absence of ganglion cells in the myenteric plexus of the esophagus
D: Absence of ganglion cells in the myenteric plexus of the esophagus
Answer: D: Absence of ganglion cells in the myenteric plexus of the esophagus 
Explanation: Hirschsprung's disease is a congenital disorder of the colon in which ceain nerve cells, known as ganglion cells, are absent, causing chronic constipation. The lack of ganglion cells is in the myenteric plexus (Auerbach's plexus), which is responsible for moving food in the intestine. Ref Davidson edition23rd pg 796