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: Unknown
[{'content': 'In Barrett esophagus, esophageal lining is changed to: \nSelect and explain. \nA. Squamous epithelium, B. Columnar epithelium, C. Pseudostratified epithelium, D. None of the above', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Barrett esophagus is a metaplasia of the esophageal mucosa caused by the replacement of the squamous epithelium with columnar epithelium.', 'role': 'assistant'}]