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
A patient presenting with progressive dysphagia and in Barium shows bird-beak appearance. What is the Investigation of Choice? 
Select and explain. 
A. Manometry, B. pH monitoring, C. Endoscopy, D. CECT scan
A: Manometry
Answer: A: Manometry 
Explanation: Ans. (a) ManometryRef: Sabiston 20th Edition, Page 1018* IOC for Achalasia Cardia is Manometry.* Three types of Achalasia cardia are there as per Chicago Classification