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': 'Dosage of benzyl penicillin in treatment of primary syphiis is - \nSelect and explain. \nA. 1.2 MU single i.m., B. 1.2 MU single i.v., C. 2.4 MU single i.m., D. 4.8 MU single i.m.', 'role': 'user'}, {'content': "Answer: C \nExplanation: Ans. is 'c' i.e., 2.4 MU single i.m.", 'role': 'assistant'}]