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': 'Hand over mouth exercise (HOME) is an effective behavioral modification technique in the age group of: \nSelect and explain. \nA. 3 to 6 years, B. Under 3 years, C. 6 to 9 years, D. Above 9 years', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]