So let's begin with factor I. Factor I is a protein that can basically deactivate the C three B molecule. So the C three B molecule that needs to be used with factor B to form this complex can basically be activated by factor I. And once we deactivate this, it cannot combine with factor B, and so it cannot follow this alternative pathway. Now, another protein is factor H. And factor H actually removes the BB protein from this complex, once again, deactivating this pathway. And finally, we also have another important agent that plays a role in the classical pathway, and that is the C one inhibitor.