A 3-month-old child presents with intermittent stridor. Most likely cause is

Stridor is a common presenting symptom in young children and is produced by turbulent flow through the upper airway or trachea. In children under 12 months of age, stridor is commonly caused by laryngomalacia, tracheomalacia, croup, airway foreign body, and/or retropharyngeal abscess. Reference: GHAI Essential pediatrics, 8th edition