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
Pathology of endometriosis is best explained by 
Select and explain. 
A. Coelemic metaplasia, B. Endometrial hyperplasia, C. Retrograde menstruation, D. Intraperitoneal immunologic deficit
C: Retrograde menstruation
Answer: C: Retrograde menstruation 
Explanation: Retrograde menstruation is the most acceptable theory