Final answer:
The three complement pathways that can be activated are the classical pathway, the lectin pathway, and the alternative pathway.
Step-by-step explanation:
The three complement pathways are the classical pathway, the lectin pathway, and the alternative pathway. The classical pathway is activated by the binding of antibodies to a pathogen surface. The lectin pathway is activated by the binding of certain acute-phase proteins to a pathogen surface. The alternative pathway is activated by the spontaneous activation of complement protein C3.