This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T, Subject name: Surgery
First line drug for prophylaxis of pneumocystosis is 
Select and explain. 
A. TMP-SMX, B. Dapsone, C. Pyrimethamine, D. Atovaquone
A: TMP-SMX
Answer: A: TMP-SMX 
Explanation: First line drug for prophylaxis of pneumocystosis is TMP-SMX (trimethoprim-sulfamethoxazole).Dapsone, Pyrimethamine, Atovaquone, Leucovorin, Pentamidine are second line drugs