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': 'Cause of unilateral dysmenorrhea : \nSelect and explain. \nA. One horn of malformed uterus, B. Endometriosis with unilateral distribution, C. Small fibroid at the utero tubal junction, D. All of the above', 'role': 'user'}, {'content': 'Answer: D \nExplanation: All of the above', 'role': 'assistant'}]