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': 'The most common chromosomal syndrome is – \nSelect and explain. \nA. Fragile X-syndrome, B. Trisomy 17, C. Trisomy 21, D. Trisomy 13', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Down syndrome (Trisomy) is the most common of the chromosomal disorder. It occurs in frequency of 1:800 to 1:1000 newborn.', 'role': 'assistant'}]