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
Most common cause of UTI in young females is? 
Select and explain. 
A. Staph saprophyticus, B. E.coli, C. Klebsiella, D. Proteus
B: E.coli
Answer: B: E.coli 
Explanation: Ans. (b) E.coliRef: Harrison's 17/e /1820-1823