A 2-year-old child presents to the emergency department with a barking cough, stridor, and a hoarse voice that worsens at night. The child is afebrile but appears anxious and has labored breathing. The nurse suspects croup as the diagnosis. Which of the following interventions should the nurse prioritize to manage the child's symptoms and prevent further respiratory distress?

A. Croup is usually viral in origin (most commonly parainfluenza virus), so antibiotics are not indicated unless there is evidence of a secondary bacterial infection. Routine antibiotic administration does not improve viral croup and can contribute to antibiotic resistance. B. Placing the child in a supine position may worsen airway obstruction and increase respiratory effort. Children with croup often assume an upright or sitting position to maximize airway patency and ease breathing. C. Encouraging the child to lie down to conserve energy is not appropriate. Lying down can exacerbate airway obstruction in croup, increase stridor, and worsen respiratory distress. D. Providing a cool mist humidifier or taking the child outside into cool night air helps reduce airway inflammation and swelling in the upper airway. Cool air can soothe the larynx, decrease stridor, and ease the barking cough. These noninvasive measures are first-line interventions to manage mild to moderate croup and prevent progression to severe respiratory distress. Supporting the child in an upright, calm position while monitoring oxygenation and respiratory effort is also essential.