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': 'The most common malignant orbital tumor in children is: \nSelect and explain. \nA. Rhabdomyosarcoma, B. Cavernous Hemangioma, C. ALL, D. AML', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The most common malignant orbital tumour in children is Rhabdomyosarcoma. Rhabdomyosarcoma is the most common primary malignant orbital tumor in the pediatric age group. Ref: Head & neck surgery - otolaryngology: Volume 2 - Page 1501; Recent Advances in Ophthalmology - Volume 9 - Page 48.', 'role': 'assistant'}]