This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Disorders in Menstruation, Subject name: Gynaecology & Obstetrics
[{'content': 'Percentage of females with oligomenorrhea in PCOs: \nSelect and explain. \nA. 50%, B. 60%, C. 70%, D. 80%', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ans. is d, i.e. 80%Ref: Shaw 15th/ed, p370Patients of PCOS develop early oligomenorrhea (87%) or short period of amenorrhea (26%) followed by prolonged periods.', 'role': 'assistant'}]