<prompt> Trophoblast differentiates at _ post-fertilization day?8-Jun12-Aug14-Dec16-18  <response>: Ans. a. 6-8 Explanation: Trophoblast differentiates into cyto and syncytiotrophoblast at 6 - 8th-day post ovulationfertilization. The references are from Grays anatomy, Langman Embryology, and Moore Embryology. 