A 6-hour-old term neonate presents with central cyanosis of the lips, tongue, and mucosa. The pediatrician performs a hyperoxia test by administering 100% inspired oxygen for 10 minutes and measures arterial blood gas. The finding marked **B** in the diagram — NO improvement with the hyperoxia test (pO2 remains <100 mmHg) — is observed. Which of the following is the MOST LIKELY diagnosis in this neonate?