This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Gynaecology, Subject name: Gynaecology & Obstetrics
[{'content': 'Pathology of endometriosis is best explained by \nSelect and explain. \nA. Coelemic metaplasia, B. Endometrial hyperplasia, C. Retrograde menstruation, D. Intraperitoneal immunologic deficit', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Retrograde menstruation is the most acceptable theory', 'role': 'assistant'}]