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': 'Ground water has the following advantages except – \nSelect and explain. \nA. Likely to be free from pathogenic organisms, B. Usually requires no treatment, C. Supply is likely to be certain even during dry season, D. Likely to be hard', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ground water is hard, but it is a disadvantage (not advantage).\nGround water\n\nGround water is the cheapest and most practical means of providing water to small quantities.\nGround water is superior to surface water, because the ground itself provides an effective filtering medium.\n\nAdvantages\n\nIt is likely to be free from pathogenic agents.\nRequires no treatment (disinfection).\nThe supply is likely to be certain even during dry season.\nIt is less subject to contamination than surface water.\n\nDisadvantages\n\nIt is high in mineral content e.g., salts and magnesium which render the water hard.\nIt requires pumping or some arrangement to lift the water.', 'role': 'assistant'}]