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: Dental
[{'content': 'The ugly duckling stage is seen at the age of \nSelect and explain. \nA. 6 - 7 years, B. 9 -10 years, C. 10 - 12 years, D. 12 - 14 years', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]