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 toxic intraocular foreign body is a paicle of: \nSelect and explain. \nA. Copper, B. Iron, C. Tantalum, D. Aluminium', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. Copper', 'role': 'assistant'}]