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
[{'content': "Infant with no social smile, no eyebrows, protruded tongue. Diagnosis – \nSelect and explain. \nA. Cretinism, B. Down's syndrome, C. Mucopolysaccharidosis, D. Rickets", 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]