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
The most common second malignant in survivors of retinoblastoma is: 
Select and explain. 
A. Thyroid cancer, B. Nasopharyngeal carcinoma, C. Optic glioma, D. Osteosarcoma
D: Osteosarcoma
Answer: D: Osteosarcoma 
Explanation: D i.e. Osteosarcoma