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: Pathology
[{'content': "The most important prognostic factor of Wilms' tumor - \nSelect and explain. \nA. Histopathology, B. Ploidy of cells, C. Age < 1 yr, D. Mutation of c 1 p gene", 'role': 'user'}, {'content': 'Answer: A \nExplanation: Anaplastic nuclear change is the only criterion of "unfavourable" histology in Wilm\'s tumor and all Wilm\'s tumor lacking this feature are designated as having "favourable histology".\nAnaplastic nuclear change reflects extreme polypoidy & is usually apparent under low magnification.\xa0\n\n"Anaplastic histology remains a critical determinant of adverse prognosis. Even anaplasia restricted to kidney\xa0confers an increased risk of recurrence & death, underscoring the need for correctly identifying this histologic\xa0features." —Robbin\'s 8th/e pg 481', 'role': 'assistant'}]