Opsonin among the following?

Opsonization and phagocytosis: C3b and its cleavage product iC3b (inactive C3b), when fixed to a microbialcell wall, act as opsonins and promote phagocytosis by neutrophils and macrophages, which bear cell surface receptors for the complement fragments.Ref: Robbins and Cotran Pathologic Basis of Disease; 9th edition; Chapter 3; Inflammation and Repair; Page no:89