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: Medicine
[{'content': 'Radiotherapy is not used in - \nSelect and explain. \nA. Ca oesophagus ;, B. Ca cervix, C. Ca stomach, D. Brain tumour', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]