This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General obstetrics, Subject name: Gynaecology & Obstetrics
[{'content': 'embryo implants on the endometrium after--------of feilisation : \nSelect and explain. \nA. 3-5 days, B. 7-9 days, C. 10 days, D. 16 days', 'role': 'user'}, {'content': "Answer: B \nExplanation: 6-7 days after feilisation, the embryo implants the uterine wall. Reference : william's Textbook of Obstetrics 4th edition page no 89", 'role': 'assistant'}]