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: Social & Preventive Medicine
[{'content': 'Spermicide used in the contraceptive today: \nSelect and explain. \nA. Norethinosterol, B. Nonoxynol, C. DMPA, D. NET-EN', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Nonoxynol', 'role': 'assistant'}]