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: Pediatrics
Which of the following is a preventable cause of mental retardation - 
Select and explain. 
A. Hypothyroidism, B. Down syndrome, C. Cerebral palsy, D. All of the above
A: Hypothyroidism
Answer: A: Hypothyroidism 
Explanation: Ans. is 'a' i.e., Hypothyroidism Adequate care for prevention of hypothyoid state can prevent mental retardation in hypothyroidism. Down's syndrome and cerebral palsy are congenital causes of mental retardation and prevention of mental retardation would be possible only by prvention of the syndrome itself.