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 impoant prognostic indicator of mesenchymal tumour is - \nSelect and explain. \nA. Type of primary, B. Type of primary, C. Size, D. Site', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Grade", 'role': 'assistant'}]