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': '1 meq/ L of hardness of water is equivalent to presence of: \nSelect and explain. \nA. 25 mg calcium bicarbonate in 1 litre of water, B. 50 mg calcium bicarbonate in 1 litre of water, C. 100 mg calcium bicarbonate in 1 litre of water, D. 150 mg calcium bicarbonate in 1 litre of water', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Hardness of water is expressed in meq/L. 1 meq/L of hardness producing ion is equal to 5o mg of calcium bicarbonate in 1 litre of water. Ref: Park 21st edition page: 671.', 'role': 'assistant'}]