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: Social & Preventive Medicine
[{'content': 'Temporary hardness of water is due to \nSelect and explain. \nA. Calcium and magnesium Bicarbonate, B. Calcium and magnesium carbonate, C. Potassium carbonate, D. Chlorine', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]