This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Environment and health, Subject name: Social & Preventive Medicine
[{'content': 'Level of hardness in soft water \nSelect and explain. \nA. < 1meq/L, B. 1-3meq/L, C. 3-6meq/L, D. >6meq/L', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Soft water: < 1 mEq/LModerately hard: 1-3 mEq/LHard water: 3-6 mEq/LVery hard water: >6 mEq/LPark 23e pg: 727', 'role': 'assistant'}]