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': 'Best method of detection of retained glass intraocular foreign body is: \nSelect and explain. \nA. CT scan, B. Radiography, C. Ultrasonography, D. Tonography', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. CT scan', 'role': 'assistant'}]