This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteria, Subject name: Microbiology
The subarachnoid space inflammation of bacterial meningitis, which is caused by a gram-negative bacterium, is induced by which one component of the bacteria? 
Select and explain. 
A. Matrix protein, B. Lipopolysaccharide (LPS), C. Pili, D. Inner membrane
B: Lipopolysaccharide (LPS)
Answer: B: Lipopolysaccharide (LPS) 
Explanation: Ans. B. Lipopolysaccharide (LPS)ENDOTOXINS: are part of the outer cell wall of gram negative bacteria.* Lipopolysaccharides consists of three components:(1) Lipid A(2) Core polysaccharide(3) O polysaccharide* The biological activity of endo toxin is associated with the lipid A portion of LPS.