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': 'Most toxic intraocular foreign body is: \nSelect and explain. \nA. Glass, B. Iron, C. Lead, D. Copper', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Iron', 'role': 'assistant'}]