This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Social & Preventive Medicine
According to the WHO, what is the minimum bacteriological standard for drinking water 
Select and explain. 
A. All the samples should not contain coliform organisms, B. 3 consecutive samples of water should not contain any coliforms, C. 3 coliforms in a 100 ml water, D. 1 coliform in a 100 ml water
A: All the samples should not contain coliform organisms
Answer: A: All the samples should not contain coliform organisms 
Explanation: (A) All the samples should not contain coliform organisms > All water intended for drinking, E. coli or thermotolerant coliform must not be detectable in any 100 ml sample / bacteria