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': 'Criteria for drinking water quality recommended by WHO includes – a)  Colour < 15 TCUb)  pH 6.5–8.5c)  Chloride 200–600 mg/1d)  Turbidity <5 NTUe) Zinc < 4 mg/1 \nSelect and explain. \nA. bcde, B. abce, C. acde, D. abde', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Guidelines of for drinking water\n\nColour < 15 true colour units (TCU)\nTurbidity < 1 nephlometric turbidity units (NTU) (has been changed in 22nd /e of Park) \nHardness < 100 — 300 mg/litre calcium ion\npH: 6.5 — 8.5\nTotal dissolved solids (TDS) < 600 mg/litre\nChloride \xa0 \xa0200 - 600 mg/L\n\xa0H2S\xa0< 0.05 mg/L\nIron < 0.3 mg/L\nSodium < 200 mg/L\nSulphate < 250 mg/L\nZinc\xa0< 4 nag/L\nNH3\xa0< 1.50 mg/L\nFluorine < 1.5 ppm (0.5 — 0.8 ppm: Optimum level)\nNitrates < 50 mg/litre\nNitrites < 3 mg/litre\nGross alpha radiological activity < 0.1 Bq/litre\nGross beta radiological activity < 1.0 Bq/litre\nZero pathogenic microorganisms\nZero infectious viruses\nAbsence of pathogenic protozoa and infective stages of helminthes\nDissolved O2 has indirect effect, level is not specified.', 'role': 'assistant'}]