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: Pathology
[{'content': 'Sideroblastic anemia is caused due to: \nSelect and explain. \nA. Mercury, B. Lead, C. Arsenic, D. Iron', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]