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
Implantation occurs on the : 
Select and explain. 
A. 4th day, B. 6th day, C. 3th day, D. 8th day
D: 8th day
Answer: D: 8th day 
Explanation: 8th day