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': "Which of the following is most commonly responsible for traveler's diarrhea? \nSelect and explain. \nA. E.coli, B. Rotavirus, C. Shigella, D. Ascaria", 'role': 'user'}, {'content': "Answer: A \nExplanation: Traveler's Diarrhea is defined as three or more unformed stools in 24 hours passed by a traveler, commonly accompanied by abdominal cramps, nausea, and bloating. Its diagnosis does not imply a specific organism, but enterotoxigenic Escherichia coli is the most commonly isolated pathogen. Most cases are self-limited. Rotavirus causes watery diarrhea.", 'role': 'assistant'}]