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: Microbiology
[{'content': "Traveller's diarrhoea is caused by- \nSelect and explain. \nA. Shigella, B. E. Coli, C. E. histolytica, D. Giardiasis", 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]