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: Gynaecology & Obstetrics
[{'content': 'Best contraceptive for a 20 year nulliparous woman is - \nSelect and explain. \nA. IUCD, B. Pills, C. Condoms, D. Foam tablets', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Pills', 'role': 'assistant'}]