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: Unknown
Trophoblast differentiates at _ post-fertilization day? 
Select and explain. 
A. 8-Jun, B. 12-Aug, C. 14-Dec, D. 16-18
A: 8-Jun
Answer: A: 8-Jun 
Explanation: Ans. a. 6-8 Explanation: Trophoblast differentiates into cyto and syncytiotrophoblast at 6 - 8th-day post ovulation/fertilization. The references are from Gray's anatomy, Langman Embryology, and Moore Embryology.