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': "Barrett's oesophagus is : \nSelect and explain. \nA. Lower oesophagus lined by columnar epithelium, B. Upper oesophagus lined by columnar epithelium, C. Lower oesophagus lined by ciliated epithelium, D. Lower oesophagus lined by pseudostratified epithelium", 'role': 'user'}, {'content': 'Answer: A \nExplanation: Barrett\'s esophagus \n\nIs metaplastic change of distal esophageal mucosa from normal squamous epithelium to columnar epithelium, in response to chronic gastro-esophageal reflux.\nThe junction between squamous esophageal mucosa and gastric mucosa moves proximally\nThree types of columnar epithelium have been described in Barrett\'s esophagus:\n\n\nintestinal type - the most common type\nthe junctional type and\nthe gastric fundic type\n\n\nBarrett\'s esophagus is a premalignant condition for adenocarcinoma esophagus\n"The definition of Barrett\'s esophagus (BE) has evolved considerably over the past decade. Traditionally, BE was identified by the presence of columnar mucosa extending at least 3 cm into the esophagus. It is now recognized that the specialized intestinal type epithelium found in the Barrett\'s mucosa is the only tissue predisposed to malignant degeneration. Consequently, the diagnosis of BE is presently made given any length of endoscopically indentifiable columnar mucosa that proves on biopsy to show intestinal metaplasia." - Schwartz 9/e p831 (8/e, p868)\n\nAlso remember\n\nThe hallmark of intestinal metaplasia is the presence of intestinal goblet cells.', 'role': 'assistant'}]