This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.V.S, Subject name: Pediatrics
[{'content': 'In which of the following conditions left atrium is not enlarged \nSelect and explain. \nA. Ventricular septal defect, B. Atrial septal defect, C. Aoopulmonary window, D. Patent ductus aeriosus', 'role': 'user'}, {'content': 'Answer: B \nExplanation: In ASD left atrium does not enlarge unless associated with other anomalies like mitral regurgitation . Ref : Ghai essential of pediatrics,eighth edition P.no: 413', 'role': 'assistant'}]