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
Swarming growth on culture is characteristic of which Gram-negative organism- 
Select and explain. 
A. Clostridium welchii, B. Clostridium tetani, C. Bacillus cereus, D. Proteus mirabilis
D: Proteus mirabilis
Answer: D: Proteus mirabilis 
Explanation: None