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 and permanent removed by – \nSelect and explain. \nA. Boiling, B. Addition of lime, C. Permutit method, D. All', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Permutit method (Base exchange process) can remove both permanent and temporary hardness.', 'role': 'assistant'}]