This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Tumors, Subject name: Ophthalmology
[{'content': 'Most common orbital tumor in children- \nSelect and explain. \nA. Rhabdomyosarcoma, B. Retinoblastoma, C. Melanoma, D. Chloroma', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Malignant tumor arise from pleuripotent mesenchymal cells , seen in childrens below 15yrs of age and common in adults Ref : ak khurana 6th edition', 'role': 'assistant'}]