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: Medicine
[{'content': 'Bronchial hyperplasia may be caused by all except \nSelect and explain. \nA. Smoking, B. Theophylline, C. Prematurity, D. Allergy', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]