One year ago, a 2-year-old child had an illness characterized by a high fever. Staphylococcus epidermidis was cultured from the blood. The child was given antibiotic therapy and recovered. Now on physical examination, a harsh, waxing and waning, machinery-like murmur is heard on auscultation of the upper chest. A chest radiograph shows prominence of the pulmonary arteries. Echocardiography shows all valves to be normal in configuration. Laboratory studies show normal arterial oxygen saturation level. Which of the following congenital heart diseases is most likely to explain these findings? (A) Atrial septal defect (B) Tetralogy of Fallot (C) Aortic coarctation (D) Total anomalous pulmonary venous return (E) Patent ductus arterios us (F) Aortic atresia