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: Pediatrics
[{'content': 'A mother brought her 7 year old daughter complaining of breast development. Thelarche occurs normally at? \nSelect and explain. \nA. 7-11 years, B. 8-13 years, C. 11-13 years, D. 12-14 years', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Breast development, termed thelarche, begins in most girls between the ages of 8 and 13 years. Thelarche prior to age 8 or lack of breast development by age 13 is considered abnormal and should be investigated. Ref: Hoffman B.L., Schorge J.O., Schaffer J.I., Halvorson L.M., Bradshaw K.D., Cunningham F.G., Calver L.E. (2012). Chapter 14. Pediatric Gynecology. In B.L. Hoffman, J.O. Schorge, J.I. Schaffer, L.M. Halvorson, K.D. Bradshaw, F.G. Cunningham, L.E. Calver (Eds), Williams Gynecology, 2e.', 'role': 'assistant'}]