The most common cause of laryngeal stridor in a 60 years old male is:

(c) Carcinoma larynx(Ref. Cummings, 6th ed., 1612)At this age laryngeal stridor is most commonly caused by carcinoma of the larynx.Patients of nasopharyngeal carcinoma do not have stridor.Acute severe asthma will lead to wheeze.Patients of Reinke's edema have hoarseness and not stridor.