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: Biochemistry
[{'content': 'Which is non essential mineral \nSelect and explain. \nA. Sodium, B. Manganese, C. Iron, D. Lead', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Lead is non-essential toxic mineral.', 'role': 'assistant'}]