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
Most common second malignancy in patients with familial retinoblastoma is: 
Select and explain. 
A. Teratoma, B. Medullary carcinoma, C. Osteosarcoma, D. Malignant melanoma
C: Osteosarcoma
Answer: C: Osteosarcoma 
Explanation: Ans. Osteosarcoma