Acute stridor in an infant could be suggestive of:

Rationale: A. Pneumonia typically causes crackles, wheezing, fever, and cough, but not acute stridor. B. Epiglottitis is a life-threatening condition in infants and young children that causes acute stridor, drooling, fever, and respiratory distress. Stridor is a hallmark sign of upper airway obstruction in this scenario. C. Bronchiolitis usually causes wheezing and respiratory distress, but stridor is less common unless severe upper airway involvement occurs. D. Apnea refers to pauses in breathing and may be associated with cyanosis or bradycardia but does not cause stridor.