This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pediatrics
Following is not a cause of stridor in infants 
Select and explain. 
A. Croup, B. Laryngomalacia, C. Retropharyngeal abscers, D. Bronchiolitis
D: Bronchiolitis
Answer: D: Bronchiolitis 
Explanation: None