A 7-year-old boy with a history of cyanotic heart disease presents to the emergency department with acute worsening of dyspnea and cyanosis. Physical examination reveals severe cyanosis, a single loud S2, and diminished pulmonary vascular markings on chest X-ray. Over the past year, his parents report he has had progressively severe exercise intolerance. When examined, he demonstrates a 'boot-shaped' heart on imaging. An echocardiogram reveals absence of the tricuspid valve, a hypoplastic right ventricle, and right-to-left shunting across a patent foramen ovale. The child's arterial oxygen saturation is 65% on room air. Which of the following is the most likely diagnosis?

1. A)Tetralogy of Fallot
2. B)Transposition of the great arteries
3. C)Total anomalous pulmonary venous return
4. D)Hypoplastic left heart syndrome
5. E)Tricuspid atresiaGABARITO