A term infant has initial Apgar scores of 8 and 10 at 1 and 5 minutes. On auscultation of the chest, a heart murmur is audible. There is hepatosplenomegaly. Cataracts of the crystalline lens are noted. The infant is at the 30th percentile for height and weight. Echocardiography shows a patent ductus arteriosus. Which of the following events is the most likely risk factor for the findings in this infant?
Congenital rubella infection Dietary folate deficiency Dispermy at conception Erythroblastosis fetalis