A 4-year-old boy is brought to the ED by his parents for difficulty breathing. His mother reports that he developed nasal congestion and malaise 2 days ago, but over the past 12 h, he has had continuous low-pitched coughs. His temperature is 101 ° F. On physical exam, he has pharyngeal erythema, cervical lymphadenopathy, and inspiratory stridor. Neck radiograph shows subglottic narrowing of the airway. He appears to be in respiratory distress and subsequently requires rapid sequence intubation. What is the most likely diagnosis?
(A) Respiratory distress syndrome
(B) Epiglottitis
(C) Laryngotracheobronchitis
(D) Bronchiolitis
(E) Laryngomalacia