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
[{'content': 'Most common second malignancy in patients with familial retinoblastoma is: \nSelect and explain. \nA. Teratoma, B. Medullary carcinoma, C. Osteosarcoma, D. Malignant melanoma', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. Osteosarcoma', 'role': 'assistant'}]