This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Child Psychiatry, Subject name: Psychiatry
[{'content': "Which of the following disorders may be diagnosed even if the onset is after age 18 years? \nSelect and explain. \nA. Tourette's disorder, B. Chronic motor or vocal tic disorder, C. Transient tic disorder, D. Tic disorder not otherwise specified", 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans. D. Tic disorder not otherwise specifiedAll tic disorders with onset after age 18 years must be diagnosed as tic disorder not otherwise specified, a residual category for tics that do not meet the criteria for a specific tic disorder. Transient tic disorder, chronic motor or vocal tic disorder, and Tourette's disorder all specify onset before age 18 years.", 'role': 'assistant'}]