Answer :
Final answer:
The two major pathways for complement activation are the Classical and Alternative pathways, hence the correct answer is a. Classical pathway and Alternative pathway.
Explanation:
Two of the major means of activation of complement following the entry of a pathogen into the body are the Classical pathway and the Alternative pathway.
The classical pathway is initiated when an acute-phase protein such as C-reactive protein (CRP) or an antibody binds to a pathogen.
Specifically, the binding of CRP during the acute phase response of innate immunity, or the binding of antibody molecules IgG or IgM to their specific antigen, triggers this pathway, leading to the activation of the C1 complex and a cascade of subsequent complement proteins.
