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': 'A child with a small head, minor anomalies of the face including a thin upper lip, growth delay, and developmental disability can have all of the following,except – \nSelect and explain. \nA. A chromosomal syndrome, B. A teratogenic syndrome, C. A mendelian syndrome, D. A polygenic syndrome', 'role': 'user'}, {'content': 'Answer: D \nExplanation: A syndrome with facial anomalies including a thin upper lip, growth delay and developmental disabilities is likely to result from either a teratogenic congenital malformation, a single gene defect (Mendelian) or a chromosomal disorder. A trait is called polygenic if multiple genes are thought to contribute to the phenotype and includes conditions like diabetes and hypertension. A polygenic disorder is the least likely diagnosis amongst the options provided and the single best answer of exclusion.', 'role': 'assistant'}]