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: Pharmacology
[{'content': 'Methemoglobinemia may be caused by following agents, EXCEPT: \nSelect and explain. \nA. Sulfonamides, B. Phenytoin, C. Phenacetin, D. Phenazopyridine', 'role': 'user'}, {'content': "Answer: B \nExplanation: Drugs Commonly Implicated in Patients with Methemoglobinemia: Analgesics Phenazopyridine Phenacetin Antimicrobials Antimalarials Dapsone Local anesthetics Benzocaine Lidocaine Prilocaine Dibucaine Nitrates/nitrites Amyl nitrite Isobutyl nitrite Sodium nitrite Ammonium nitrate Silver nitrate Sulfonamides Ref: Farmer B.M., Nelson L.S. (2011). Chapter 201. Dyshemoglobinemias. In J.E. Tintinalli, J.S. Stapczynski, D.M. Cline, O.J. Ma, R.K. Cydulka, G.D. Meckler (Eds), Tintinalli's Emergency Medicine: A Comprehensive Study Guide, 7e.", 'role': 'assistant'}]