This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
Amyl nitrate inhalation test is used to detect- 
Select and explain. 
A. Carcinoma esophagus, B. Achalasia cardia, C. Oesophageal diverticulum, D. Transeoesophageal fistula
B: Achalasia cardia
Answer: B: Achalasia cardia 
Explanation: None