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': '\\r\\n\\r\\n\\r\\n \\r\\nWhat should be the hardness level of drinking water?\\r\\n\\r\\n \nSelect and explain. \nA. Soft water, B. Moderately hard water, C. Hard water, D. Very hard water', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Drinking water should be moderately soft. Softening of water is recommended when hardness exceeds 3 meq/ L. Ref: Park 21st edition page: 672.', 'role': 'assistant'}]