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': 'Which among the following carcinoma is treated by radiotherapy? \nSelect and explain. \nA. Supraglottic Ca T3 N0, B. Nasopharyngeal Ca T3 N1, C. Glottic CaT3 N1, D. Subglottic Ca T3 N0', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Over 95% of endemic nasopharyngeal carcinomas (NPC) are classified as WHO type 3 and associated with EBV. NPC tends to occur in younger persons and is not associated with tobacco usage. NPC is an aggressive neoplasm with cervical lymph node metastases present in 60 to 90% of patients at diagnosis. Because of unique anatomic, biological, and clinical characteristics, therapy for NPC is distinctive. Radiotherapy is the mainstay of local therapy. NPCs are highly chemoradiosensitive. Intensity-modulated radiation therapy (IM) allows for greater conformality of the high-dose regions with relative sparing of adjacent normal tissues compared to traditional radiation techniques.', 'role': 'assistant'}]