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
Which of the following is late lactose fermenter ? 
Select and explain. 
A. E coli, B. Klebsiella, C. Salmonella, D. Shigella sonnei
D: Shigella sonnei
Answer: D: Shigella sonnei 
Explanation: Ans. is 'd' i.e., Shigella sonnei Lactose fermenters produce pink/bright red colonies on MacConkey's agar , while lactose non-fermenters produce pale colonies :Lactose fermenters (rapid) : These are Coliforms, e.g. Escherichia, Klebsiella and Enterobacter aerogenes.Late lactose fermenters (slow): These are Shigella Sonnei, Serratia, Citrobacter, Arizona, Providencia and Ervinia.Non-lactose fermenters : Shigella except Shigella Sonnei, Salmonella, Proteus