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': 'Commonest cause of enlarged cardiac shadow in X-ray of a child is - \nSelect and explain. \nA. PDA, B. Coarctation of Aoa, C. Pericarditis, D. Rheumatic carditis', 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans. is 'd' i.e., Rheumatic carditis o Cardiac failure causes cardiomegaly o MC cause of cardiac failure in children (elder than infants) is rheumatic fever and rheumatic hea disease.", 'role': 'assistant'}]