Which measure would be most effective in aiding bronchodilation in a child with laryngotracheobronchitis (Croup)?

A. Offering oral fluids can help keep the child hydrated but does not directly aid in bronchodilation. B. Oral analgesics may help with pain but do not address airway obstruction or inflammation. C. Racemic epinephrine nebulizer therapy is effective in reducing airway swelling and providing bronchodilation, improving breathing in croup. D. Teaching the child to take long, slow breaths can help with calmness but is not as effective in acute bronchodilation.