What is the end product of complement activation?

The end product of complement activation is indeed cell lysis. This process occurs when the complement system, a group of proteins in the blood, is activated and leads to the formation of the membrane attack complex (MAC). The MAC inserts itself into the membrane of target cells, particularly pathogens like bacteria, resulting in disruption of the membrane integrity and eventually causing the cell to lyse, or burst.

While other options in the question relate to important immunological processes, they do not directly result from complement activation. Cell division, for example, pertains to the proliferation of immune cells in response to an antigen but is not a product of the complement cascade. Antibody production is tied to B cell activation and differentiation, functions regulated by various immune signals but not directly by complement activation. Immune memory refers to the long-term presence of memory cells that arise after an immune response, allowing for quicker responses upon re-exposure to the same antigen, which again is not a direct outcome of complement activation.

Thus, the direct outcome of complement activation clearly demonstrates its critical role in immune defense through the mechanism of cell lysis.