Which of the following is a classic symptom of tetralogy of Fallot?

Tetralogy of Fallot is a congenital heart defect characterized by a combination of four distinct abnormalities: a ventricular septal defect (VSD), pulmonary stenosis (narrowing of the outflow tract from the right ventricle to the pulmonary artery), right ventricular hypertrophy (thickening of the muscular walls of the right ventricle), and an overriding aorta (where the aorta is positioned directly over the ventricular septal defect, rather than arising from the left ventricle).

Among these features, a ventricular septal defect is a classic and defining characteristic of tetralogy of Fallot. It allows blood to flow from the left ventricle to the right ventricle, leading to increased pulmonary blood flow and contributing to the clinical manifestations of the condition, such as cyanosis due to decreased oxygenated blood reaching the body. The presence of a VSD is fundamentally important in the pathophysiology of tetralogy of Fallot, making it a key symptom.

The other options, while they do represent types of congenital heart defects, are not part of the classic tetralogy of Fallot triad. For instance, pulmonary artery atresia is a more severe form of blockage that does not characterize tet