What is the blood type When neither anti-A sera nor anti-B clot on a plate with donor blood?

When neither anti-A sera nor anti-B sera clot on a plate with donor blood, the blood type is O. This is because type O blood does not have any A or B antigens on the surface of its red blood cells. As a result, neither anti-A nor anti-B sera will be able to bind to the red blood cells and cause them to clot.