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
Indication of fecal contamination of water is due to presence of all, EXCEPT: 
Select and explain. 
A. Enterococci, B. Coliform, C. E.coli, D. Clostridium difficile
D: Clostridium difficile
Answer: D: Clostridium difficile 
Explanation: The primary bacterial indicator recommended for this purpose is the coliform group of organism. Supplementary indicator organisms are: Fecal group: E.coli, Fecal streptococci and sulphite reducing bacteria Non Fecal group: Klebsiella aerogenes. Clostridium perfringens: The spores are capable of surviving in water for a longer time than organism of the coliform group & usually resistant chlorination. Ref: Park, 20th Edition, Page 630