This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Behavioral Disorders in Children, Subject name: Pediatrics
[{'content': 'Which of the following is not true regarding "thumb sucking"? \nSelect and explain. \nA. Is a sign of insecurity, B. Pleasurable sensation, C. Leads to dental problems, D. Seen only in child < 4 years of age', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Thumb sucking: common in infancy and in as many as 25% of children age 2 yr and 15% of children age 5 yr. self-soothing behavior Leads to dental problems T/t- Behavioural therapy', 'role': 'assistant'}]