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
[{'content': "Which of the following is investigation of choice for Zenker's diveiculum? \nSelect and explain. \nA. CECT, B. Endoscopy, C. Esophageal manometry, D. Barium swallow", 'role': 'user'}, {'content': 'Answer: D \nExplanation: When suspected, the diagnosis is established by a barium swallow.. Endoscopy is usually difficult in the presence of a cricopharyngeus diveiculum and potentially dangerous, owing to the obstruction of the true esophageal lumen by the diveiculum and the associated risk of diveicular perforation. Ref: Schwaz 9/e, Page 848.', 'role': 'assistant'}]