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: ENT
All of the following constitute supraglottic cancer except: 
Select and explain. 
A. Vallecula, B. Lower border of cricoid, C. Posterior commisure, D. All
D: All
Answer: D: All 
Explanation: The lingual surface of the epiglottis and valleculae are in the oropharynx. The glottis comprises the vocal cords and the anterior and posterior cornmissures. Subglottis is a small area extending from the lower border of the cricoids to the under surface of the vocal cords