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: Pediatrics
Most common secondary tumor with Retinoblastoma is 
Select and explain. 
A. Neuroblastoma, B. Pineoblastoma, C. Osteochondroma, D. Osteosarcoma
D: Osteosarcoma
Answer: D: Osteosarcoma 
Explanation: Most common secondary tumor with Retinoblastoma Osteosarcoma, Soft tissue sarcoma and malignant melanoma.