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: Dental
[{'content': 'Temporary water hardness is removed by \nSelect and explain. \nA. Filtration, B. Storage, C. Addition of bleaching powder, D. Boiling', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]