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': "Tumour that doesn't show spontaneous regression: \nSelect and explain. \nA. Neuroblastoma, B. Retinoblastoma, C. Malignant melanoma, D. Osteosarcoma", 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]