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': 'Marker of fecal contaminatin is – \nSelect and explain. \nA. Ascaris, B. E. coli, C. guinea worm presence, D. Balantidium coli', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]