Which of the following congenital heart diseases is associated with right-to-left shunting?

Tetralogy of Fallot is a type of congenital heart disease characterized by a combination of four heart defects, which can lead to right-to-left shunting. In this condition, there is a defect in the ventricular septum, an obstruction in the outflow of blood from the right ventricle, and a position of the aorta that straddles both ventricles. This anatomical arrangement allows deoxygenated blood to bypass the lungs and enter systemic circulation, resulting in cyanosis and low oxygen levels in the blood, which are hallmark signs of right-to-left shunting.

In contrast, the other conditions listed do not typically involve right-to-left shunting. Patent ductus arteriosus, for instance, allows blood to flow from the aorta to the pulmonary artery but does not create a right-to-left shunt. Similarly, a ventricular septal defect primarily leads to left-to-right shunting, where oxygenated blood from the left ventricle flows into the right ventricle, thereby increasing blood flow to the lungs without shunting deoxygenated blood into the systemic circulation. Subvalvular aortic stenosis involves an obstruction below the aortic valve but does not create a direct route for deoxygenated blood to enter systemic