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: Radiology
[{'content': 'The ideal timing of radiotherapy for Wilms tumour after surgery is – \nSelect and explain. \nA. Within 10 days, B. Within 2 weeks, C. Within 3 weeks, D. Any time after surgery', 'role': 'user'}, {'content': "Answer: A \nExplanation: The postoperative radiotherapy in Willm's tumor is started within 10 days of surgery. Delay in starting RT beyond 10 days leads to tumor cell repopulation and increase in relapse rate.", 'role': 'assistant'}]