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
[{'content': 'All of the following constitute supraglottic cancer except: \nSelect and explain. \nA. Vallecula, B. Lower border of cricoid, C. Posterior commisure, D. All', 'role': 'user'}, {'content': 'Answer: D \nExplanation: 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', 'role': 'assistant'}]