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
Commonest cause of enlarged cardiac shadow in X-ray of a child is - 
Select and explain. 
A. PDA, B. Coarctation of Aoa, C. Pericarditis, D. Rheumatic carditis
D: Rheumatic carditis
Answer: D: Rheumatic carditis 
Explanation: 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.