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 metastatic orbital tumour in children \nSelect and explain. \nA. Neuroblastoma, B. Carcinoma lung, C. Ewing's sarcoma, D. Ovarian sarcoma", 'role': 'user'}, {'content': "Answer: A \nExplanation: Metastatic orbital tumours in children neuroblastoma, nephroblastoma, Ewing's, testicular embryonal sarcoma and Ovarian sarcoma.", 'role': 'assistant'}]