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: Psychiatry
[{'content': "Regression of mile stones occur after normal development upto _______ in Rett's disease \nSelect and explain. \nA. 5 months, B. 1 year, C. 2 years, D. 1 months", 'role': 'user'}, {'content': "Answer: A \nExplanation: Rett's disease is characterized by regression of milestones after normal development upto 5 months. There is also deceleration in head circumference leading to microcephaly.", 'role': 'assistant'}]