Final answer:
The three major complement activation pathways in the immune system converge with the formation of the same component, which is the splitting of the C3 protein. This component binds to the surface of the pathogen and activates the rest of the cascade, ultimately leading to the formation of the membrane-attack complex (MAC).
Step-by-step explanation:
The three major complement activation pathways in the immune system are the classical pathway, the alternative pathway, and the lectin pathway. These pathways converge with the formation of the same component, which is the splitting of the C3 protein. In both the alternative and classical pathways, C3 is split into two fragments, C3a and C3b. C3b binds to the surface of the pathogen and activates the rest of the cascade, leading to the formation of the membrane-attack complex (MAC) that can kill certain pathogens.