A 5-Year-Old Boy Was Seen in the Emergency Room Following

A 5-year-old boy was seen in the emergency room following an attack of breathlessness during which he had lost consciousness. The mother, on questioning, said that her child had had several such attacks before and sometimes his skin had become bluish. Recently she had noticed that he breathed more easily when he was playing in a squatting position; he also seemed to sleep more easily with his knees drawn up. On physical examination, the child was found to be thinner and shorter than normal. His lips were cyanotic, and his fingers and toes were clubbed. A systolic murmur was present along the left border of the sternum, and the heart was considerably enlarged to the right. An extensive workup, including angiography, demonstrated tetralogy of Fallot.
-Using your knowledge of cardiac development, critically read the following observations made in this case and determine the one that is incorrect.

A) The systolic murmur heard along the left border of the sternum was caused by the pulmonary stenosis.
B) A right-to-left shunt of blood occurs through the large ventricular septal defect.
C) The aortic blood is poorly oxygenated resulting in the impaired growth of the child, the cyanosis of the lips, and the clubbing of the fingers and toes
D) Maintaining the squatting position during play and sleeping with the knees drawn up increases the peripheral resistance in the systemic circulation and decreases the right-to-left shunt through the ventricular septum.
E) If the patient had a large ductus arteriosus as well as the tetralogy of Fallot, the cyanosis would be much worse.