And any antibody against A or B will not be able to bind to these red blood cells. And so we can easily donate type O blood to either one of these four red blood types. On the other hand, this O cannot actually receive any blood unless it's type O. And that's because if, let's say our person has type O red blood cells, that means they produce both antibodies against antigen A and antigen B. And by donating a B or AB to this person with blood type O, that means the blood type O person will have antibodies that will kill off all these different red blood cells, AB and AB. And only this one, the blood type O donator, will not have the red blood cells with either of these antigens.