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': 'Most common etiology of abnormal uterine bleeding in childhood age group \nSelect and explain. \nA. Vulvovaginitis, B. Anovulation, C. Endometrial polyp, D. endometrial cancer', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Vulvovaginitis is commonest etiology of AUB in childhood age group.', 'role': 'assistant'}]