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
[{'content': 'A patient presenting with progressive dysphagia and in Barium shows bird-beak appearance. What is the Investigation of Choice? \nSelect and explain. \nA. Manometry, B. pH monitoring, C. Endoscopy, D. CECT scan', 'role': 'user'}, {'content': 'Answer: A \nExplanation: 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', 'role': 'assistant'}]