Final answer:
The O antigen component of Lipopolysaccharide (LPS) is responsible for generating an antibody response in gram-negative bacterial infections.
Step-by-step explanation:
The component of Lipopolysaccharide (LPS) that generates an antibody response in gram-negative bacterial infections is the O side chain. The O antigen is part of the LPS structure and is composed of sugar-like molecules that make up the external face of the LPS. The composition of the O side chain varies between different species and strains of bacteria, making it the target for the immune system's antibody response. Unlike the O antigen, Lipid A is the toxic component that is responsible for the inflammatory effects of the LPS, but it is not the part that elicits the antibody response.