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': "In a child with phthisical eye of unknown etiology following possibility should be kept in mind: \nSelect and explain. \nA. Bih trauma, B. Still's disease, C. Retinoblastoma, D. Untreated congenital glaucoma", 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. Retinoblastoma', 'role': 'assistant'}]