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': 'Which is the most common second malignancy in survivors of retinoblastoma? \nSelect and explain. \nA. Optic glioma, B. Osteosarcoma, C. Thyroid cancer, D. Nasopharyngeal carcinoma', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Osteosacrcomas are the most common second malignancy in survivors of retinoblastoma. Ref: Cancer in Children and Adolescents By William Larkin Carroll, Page 384; Manual of Pediatric Hematology and Oncology By Philip Lanzkowsky, 5th Edition, Page 947', 'role': 'assistant'}]