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
Common causes of congenital stridor in child - 
Select and explain. 
A. Laryngeal web, B. Laryngomalacia, C. Haemangioma, D. Subglottic stenosis
B: Laryngomalacia
Answer: B: Laryngomalacia 
Explanation: STRIDOR

Due to upper airway obstruction,

Types -

Inspiratory stridor - Obstruction above vocal cords (supraglottic).
Expiratory stridor - Obstriction distal trachea.
Biphasic - From supragiottic or proximal tracheal.

Causes  Infective:

Croup (lanyngo tracheo bronchitis)
Bacterial trachetis
Retropharyngeal abscess

Congenital:

Laryngomalacia: 60% of all total most common cause.
Vocal cord paralysis - 2nd most common.
Subglottic stenosis - 3rd most common.  

Iatrogenic :

Long-term intubation leads to subglottic stenosis - the most common causes of Acquired stridor in children.
Neoplasm: Recurrent respiratory papilloma (RRP) MC a benign tumour and larynx.