A patient is admitted to the hospital for heart surgery to have a Tetralogy of Fallot repair. The parents are asking the nurse to explain one of the underlying causes of their child's cyanosis. Nurse Lisa is correct in her explanation when she says:

A. Aortic stenosis affects blood flow from the left ventricle to the aorta, but it is not a component of Tetralogy of Fallot. B. A patent ductus arteriosus (PDA) is a separate congenital defect and not part of Tetralogy of Fallot. C. Mitral valve regurgitation is related to left-sided heart valve dysfunction and is not a feature of this condition. D. One of the four components of Tetralogy of Fallot is a ventricular septal defect (VSD). The VSD, along with pulmonary stenosis, leads to right-to-left shunting of deoxygenated blood, which bypasses the lungs and enters systemic circulation, causing cyanosis.