This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Larynx, Subject name: ENT
The most common cause of laryngeal stridor in a 60 years old male is: 
Select and explain. 
A. Nasopharyngeal carcinoma, B. Acute severe asthma, C. Carcinoma larynx, D. Reinke's edema
C: Carcinoma larynx
Answer: C: Carcinoma larynx 
Explanation: (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.