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
------- days after ovulation does implantation takes place? 
Select and explain. 
A. 3-5 days, B. 7-9 days, C. 10-12 days, D. 13-15 days
B: 7-9 days
Answer: B: 7-9 days 
Explanation: feilisation occur within 24 hours of ovulation. 6-7 weeks after ovulation/ feilisation, the embryo implants the uterine wall Reference: William's textbook of Gynaecology 24th edition page 89