This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Enterobecteriaceae, Subject name: Microbiology
[{'content': 'Most common cause of UTI in young females is? \nSelect and explain. \nA. Staph saprophyticus, B. E.coli, C. Klebsiella, D. Proteus', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. (b) E.coliRef: Harrison's 17/e /1820-1823", 'role': 'assistant'}]