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': 'Drug of choice for syphilis during pregnancy is : \nSelect and explain. \nA. Ampicillin, B. Erythromycin, C. Benzathine penicillin, D. Tetracyclines', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]