If a persons blood type showed agglutination with all three antibodies, what is the blood type?

You have type O. Here is why. Type A blood need type A or O blood. Type B blood needs type B or O blood. Type AB blood can either have type A, B, or O blood. Type O blood can only receive type O blood. Type AB is know as the universal recipient. Type O is know as the universal donor, Hope this helps!!