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': 'A patient has carcinoma of the right tongue on its lateral border of anterior 2/3rd, with lymph node of size 4 cm in level 3 on the left side of the neck, stage of the disease is - \nSelect and explain. \nA. N0, B. N1, C. N2, D. N3', 'role': 'user'}, {'content': 'Answer: C \nExplanation: According to the American Joint Committee on Cancer (AJCC), 2002, the regional lymph node staging (N) is common to all head and neck sites, except the nasopharynx.\nSo, T classification is specific to different sites of origin while regional lymph node (N) staging is common to all head & neck sites, except the nasopharynx.', 'role': 'assistant'}]