This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Oncology, Subject name: Surgery
[{'content': 'In which case spontaneous regression is not seen? \nSelect and explain. \nA. Malignant melanoma, B. Osteosarcoma, C. Neuroblastoma, D. Choriocarcinoma', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Tumors with spontaneous regression Neuroblastoma Choriocarcinoma Renal cell carcinoma Malignant melanoma Retinoblastoma', 'role': 'assistant'}]