And so if we don't have any types of pathogens in our body, why would we want the complement system to be activated? Well, we don't. And the way that we regulate it by using many different types of proteins, for example, three proteins that are commonly used by the body to basically regulate and deactivate some of these agents are the following three proteins. 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.