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': 'In precocious females, menstruation occurs : \nSelect and explain. \nA. After 13 years of age, B. At 13 years of age, C. Less than 10 years of age, D. Below 12 years of age', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Less than 10 years of age', 'role': 'assistant'}]