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': 'The following organism because of its easy culture methods is widely used as bacteriology indicator of water pollution – \nSelect and explain. \nA. Foecal streptococci, B. Escherichia coli, C. Clostridium perfringens, D. Salmonella Typhi', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]