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
Regression of mile stones occur after normal development upto _______ in Rett's disease 
Select and explain. 
A. 5 months, B. 1 year, C. 2 years, D. 1 months
A: 5 months
Answer: A: 5 months 
Explanation: 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.