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
Drug of choice for pneumocystis carinii is? 
Select and explain. 
A. Doxycyline, B. Cotrimoxazole, C. Tetracyclines, D. Dapsone
B: Cotrimoxazole
Answer: B: Cotrimoxazole 
Explanation: Question repeated