Answer:
A. Lipid A
Explanation:
The outer membrane of Gram-negative bacteria is present outside to the thin peptidoglycan layer. The outer membrane consists of lipopolysaccharide (LPS) which is the molecule having both carbohydrates and lipids.
The lipopolysaccharide has three parts out of which lipid A is the toxin one. Lipid A is embedded in the outer membrane through its fatty acids. When lipid A enters the blood stream of the host cell, it leads to septic shock. Lipid A is heat stable and highly toxic.