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': 'Metaplasia is thought to be caused in most cases by:- \nSelect and explain. \nA. Genetic mutation, B. Oncogenic virus, C. Chronic irritation, D. Immunologic reaction', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Chronic irritation Metaplasia is commonly seen in the epithelial surfaces of the bronchial tree secondary to chronic irritation of cigarette smoke. Metaplasia may also be seen in areas of long-standing, chronic infections.', 'role': 'assistant'}]