This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory system, Subject name: Pediatrics
A 3-month-old child presents with intermittent stridor. Most likely cause is 
Select and explain. 
A. Laryngotracheobronchitis, B. Laryngomalacia, C. Respiratory obstruction, D. Foreign body aspiration
B: Laryngomalacia
Answer: B: Laryngomalacia 
Explanation: 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