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: Surgery
[{'content': 'Which of  the  following is the most common  tumour  to produce metastasis to cervical lymph nodes? \nSelect and explain. \nA. Glottic carcinoma, B. Nasopharyngeal carcinoma, C. Carcinoma base of tongue, D. Carcinoma lip', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Cervical nodal metastases may be the only manifestation of nasopharyngeal cancer.\nNodal metastases are seen in 75% of the patients, when first seen, about half of them with bilateral nodes.\nDistant metastases involve bone, lung, liver and other sites.', 'role': 'assistant'}]