B

Ventricular septal defects are the commonest congenital lesions and create high-velocity left-to-right jets that traumatize endocardium, providing an ideal nidus for bacteremia; consequently, VSDs account for the largest share of endocarditis cases among unrepaired congenital heart diseases, far exceeding ASD, PDA or isolated pulmonary stenosis [Rose 1978 PMID 694613; Dodo 1996 PMID 8853132].