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: Gynaecology & Obstetrics
[{'content': 'Teratoma arises from : \nSelect and explain. \nA. Totipotent cells, B. Mesodermal cells, C. Ectodermal cells, D. Endodermal cells', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Totipotent cells', 'role': 'assistant'}]