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': 'In which of the following malignancies histological grade is a good prognostic indicator? \nSelect and explain. \nA. Melanoma, B. Soft tissue sarcoma, C. Renal cell carcinoma, D. Lung cancer', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]