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: Ophthalmology
Second common malignancy in Patients of Retinoblastoma is: 
Select and explain. 
A. Osteoblastoma, B. Osteochondroma, C. Osteoclastoma, D. Osteosarcoma
D: Osteosarcoma
Answer: D: Osteosarcoma 
Explanation: Osteosarcoma