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': 'Not seen in faecal pollution \nSelect and explain. \nA. Staphylococcus, B. Streptococcus, C. E. coli, D. ClostridiumPerfringens', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The primary bacteriological indicators for faecal contamination are → Coliform gp. of organisms.\nSupplementary indicators are →\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\nStreptococci faecalis,\nClostridium perfringens (also k/a cl. welchi)', 'role': 'assistant'}]