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
All of the following proteus species forms indole EXCEPT: September 2004 
Select and explain. 
A. P. mirabilis, B. P. vulgaris, C. P. rettgeri, D. P. morganii
A: P. mirabilis
Answer: A: P. mirabilis 
Explanation: Ans. A i.e. P. mirabilis