This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Disorders of menstruation, Subject name: Gynaecology & Obstetrics
[{'content': 'Normal menstrual cycle duration in an adolescent is \nSelect and explain. \nA. 21 - 35 days, B. 21 - 45 days, C. 24 - 38 days, D. 24 - 45 days', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Parameters for Normal Menstrual Cycles in AdolescentsParameterNormalMenstrual cycle frequency21 - 45 daysCycle variation from cycle to cycleLess than adultsDuration of flow4 - 8 daysVolume of flow4 - 80mlParameters for Normal Menstrual Cycles in Reproductive age womenParameterNormalMenstrual cycle frequency24 - 38 daysCycle variation from cycle to cycle2 - 20 daysDuration of flow4 - 8 daysVolume of flow4 - 80ml', 'role': 'assistant'}]