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: Surgery
In which case spontaneus regression is not seen - 
Select and explain. 
A. Malignant Melanoma, B. Osteosarcoma, C. Neuroblastoma, D. Choriocarcinoma
B: Osteosarcoma
Answer: B: Osteosarcoma 
Explanation: Ans is 'b' ie Osteosarcoma