This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous (Obs), Subject name: Gynaecology & Obstetrics
[{'content': 'Average age of menopause? \nSelect and explain. \nA. 40, B. 45, C. 55, D. 60', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. B. 45* Menopause is defined as the time of cessation of ovarian function resulting in permanent amenorrhoea.* Menopause is a retrospective diagnosis as it takes 12 months of amenorrhoea to confirm that menopause has set in.* Menopause normally occurs between the ages of 45 and 50 years, the average age being 47 years.', 'role': 'assistant'}]