A nurse is caring for an infant who has Tetralogy of Fallot and notes that the infant is easily fatigued when eating. The nurse should recognize that the infant's fatigue is caused by which of the following?

A. Restricted blood flow leaving the heart: While right ventricular outflow obstruction is part of TOF, fatigue is more directly linked to hypoxia than obstruction itself. B. Increased circulation pressure to the lungs: TOF causes decreased pulmonary blood flow, not increased; this choice is inaccurate. C. Lack of adequate ventricle strength to pump blood to the body: The ventricles may hypertrophy but are not weak in strength; fatigue is due to oxygen deficit. D. Inadequate oxygenation for supporting energy metabolism: TOF causes a right-to-left shunt, leading to chronic hypoxemia, which reduces available oxygen needed for cellular energy and causes fatigue.