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: Pharmacology
[{'content': 'BAL is contraindicated in \nSelect and explain. \nA. Arsenic, B. Lead, C. Mercury, D. Iron', 'role': 'user'}, {'content': 'Answer: D \nExplanation: BAL or Dimercaprol is a chelating agent used to treat poisoning by Arsenic, Lead, Mercury and Gold.\xa0\nIt is contraindicated in Iron & Cadmium poisoning.', 'role': 'assistant'}]