<prompt> Common complement component for both the pathways is the following:C3C5ClqC8  <response>: Classic and alternate pathways lead to the production of C3b, the central molecule of the complement cascade. The presence of C3b on the surface of a microbe marks it as foreign and targets it for destruction. C3b has two impoant functions: 1 It combines with other complement components to generate C5 convease, the enzyme that leads to the production of the membrane attack complex; and 2 It opsonizes bacteria because phagocytes have receptors for C3b on their surface. Ref: Levinson W. 2012. Chapter 63. Complement. In W. Levinson Ed, Review of Medical Microbiology Immunology, 12e. 