This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Urethra & Penis, Subject name: Surgery
[{'content': 'What is the most common cause of failure of radiotherapy for stage II cervical carcinoma? \nSelect and explain. \nA. Liver metastasis, B. Bone metastasis, C. Para-aortic node metastasis, D. Resistance of the central tumor', 'role': 'user'}, {'content': 'Answer: C \nExplanation: In stage II cervical cancer, the incidence of nodal involvement is 25%-40%. Most tumors are not radioresistant, and distant metastasis (i.e., a more advanced stage) are a late complication of more advanced stages of the disease.', 'role': 'assistant'}]