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 in pregnant women with Secondary Syphilis: \nSelect and explain. \nA. Doxycycline, B. Benzathine Penicillin, C. Ceftriaxone, D. Cotrimoxazole', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Benzathine Penicillin', 'role': 'assistant'}]