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 Aorta, C. Pericarditis, D. Rheumatic carditis
D: Rheumatic carditis
Answer: D: Rheumatic carditis 
Explanation: Cardiac failure causes cardiomegaly
MC cause of cardiac failure in children (elder than infants) is rheumatic fever and rheumatic heart disease.