This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory system, Subject name: Medicine
[{'content': 'Drug of choice for pneumocystis carinii is? \nSelect and explain. \nA. Doxycyline, B. Cotrimoxazole, C. Tetracyclines, D. Dapsone', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Question repeated', 'role': 'assistant'}]