Which of the following is the commonest cause of stridor in a newborn who born at term?

Laryngomalacia is the most common cause of stridor in infants, and is also the most common congenital laryngeal abnormality, accounting for approximately 60% of cases. Stridor occurs as a result of prolapse of the supraglottic structures into the laryngeal inlet on inspiration. The epiglottis is classically described as being omega shaped and folded in upon itself so that the lateral margins lie close to each other. The aryepiglottic folds are tall, foreshoened, and thin, and the arytenoids are large with redundant mucosa. Ref: Yates P.D. (2012). Chapter 33. Stridor in Children. In A.K. Lalwani (Ed), CURRENT Diagnosis & Treatment in Otolaryngology--Head & Neck Surgery, 3e.