This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
Implantation occurs at 
Select and explain. 
A. 2-3 days, B. 6-7 days, C. 15-20 days, D. 20-25 days
B: 6-7 days
Answer: B: 6-7 days 
Explanation: HUMAN EMBRYOLOGY-INDERBIR SINGH TENTH EDITION-PAGE NO:72In humans implantation begins on the 6th day after feilization