This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: general microbiology, 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: Pr.mirfabilis & Pr.vulgaris swarms on solid culture media .discrete colonies are seen in young cultures but thereafter actively motile cells spread on the surface of the plate in successive waves to form a thin film layer in concentric circles. REF:Ananthanarayan & Panicker's Textbook of Microbiology 8th edition pg no:280-281