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
Endotoxin of gram -ve bacteria that do not cause pathogenesis of natural disease 
Select and explain. 
A. Mycobacterium, B. Klebsiella, C. Vibrio, D. E.coli
C: Vibrio
Answer: C: Vibrio 
Explanation: None