This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Development period- week 1,2,3,4, Subject name: Anatomy
[{'content': 'Zona Pellucida disappears by:- \nSelect and explain. \nA. Before ferilisation, B. During feilization, C. 5th day after feilization, D. 7th day after feilization', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Zona pellucida is thick membranous covering made up of glycoprotein, the microvilli of oocyte and follicular cells project into zona pellucida for nutrition. it prevent polyspermy and implantation. Blastocyst forms at 4th day and by the end of 5th day, zona pellucida disappears and implantation takes place at 6th -7th day after feilization.', 'role': 'assistant'}]