A 16-month-old boy presents with a 1-day history of cough and noisy breathing. He is in no respiratory distress. The mother reports a history of a cold in the family. On examination, there is a brassy, seal-like cough, and inspiratory stridor is noted. The child is playful, without retractions or respiratory distress. Which of the following is the most appropriate next step in management?
a) Nebulized racemic epinephrine
b) Antibiotics
c) Corticosteroids
d) Endotracheal intubation