This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: parasitology, Subject name: Microbiology
Cyst phase does not exist in - 
Select and explain. 
A. Gardenella vaginalis, B. Trichomonas vaginalis, C. Entamoeba hystolytica, D. Entamoeba coli
A: Gardenella vaginalis
Answer: A: Gardenella vaginalis 
Explanation: Gardnerella is a genus of Gram-variable-staining facultative anaerobic bacteria of which G. vaginalis is the only species. The organisms are small nonspore-forming, nonmotile coccobacilli.