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: ENT
[{'content': "60 years old man with foul breath, Regurgitates food eaten 3 days ago, the likely diagnosis \nSelect and explain. \nA. Loss of tone of upper esophageal sphincter, B. Zenker's Diverticulum, C. Achalasia cardia, D. Carcinoma esophagus", 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]