This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General Embryology 1, Subject name: Anatomy
[{'content': 'Teiary chorionic villi develop at? \nSelect and explain. \nA. Day 28, B. Day 25, C. Day 17, D. Day 15', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Teiary chorionic villi develop at day 17-21', 'role': 'assistant'}]