You are answering a USMLE-style medical question. Question: An 18-month-old girl is brought to the emergency department because of a cough that her parents are worried about. She has had a runny nose and a low-grade fever for the past 2 days, with some hoarseness and a rough-sounding cough that started this afternoon. This evening she began making some high-pitched sounds when taking breaths, and she seemed to be having some trouble breathing. She is alert and does not appear to be in acute distress. She has a temperature of 38.0°C (100.4 °F), with a respiratory rate of 50/min and O2 saturation of 97%. There is audible inspiratory stridor that worsens when she starts to cry during the examination. She has an occasional barking cough. Her pharynx is mildly erythematous with normal tonsils and no exudate. A frontal X-ray of the upper chest airways is obtained (shown in the image). Which of the following is the best step in management? Options: A) Anterior-posterior and lateral radiographs of the neck B) Racemic epinephrine and intramuscular corticosteroid therapy C) Intravenous antibiotics D) Trial of bronchodilator therapy and oral steroids Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.