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': 'Menstruation is defined as precocious if it starts before the child reaches the age of: \nSelect and explain. \nA. 8 years, B. 10 years, C. 14 years, D. 20 years', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Precocious puberty is the appearance of appropriate secondary sexual characters before the age of 8 years and occurrence of menstruation before 10 years of chronological age.\nAlso know : Delayed puberty : is considered delayed when the secondary sexual characters do not appear by the age of 14, and menarche is not established by 16 years of age.', 'role': 'assistant'}]