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
Maximum dilatation of esophagus occurs in: 
Select and explain. 
A. Carcinoma at gastro esophageal junction, B. Achalasia cardia, C. Stricture of lower end, D. CRUST syndrome
B: Achalasia cardia
Answer: B: Achalasia cardia 
Explanation: Ans: b (Achalasia cardia)Ref: Bailey & Love, 24,hed, p. 1017 & 23rd ed, p. 882