About ABO blood grouping?

This is simple if you understand what is actually happening here. Blood groups are comprised of sugar moieties (or antigens) that stack onto each other on the surface of the red cell. The basic unit (with no further stacks is what we call Type O-all cells have this moiety); then a certain one stacks for type A and another different one for B. Then, you make ANTIBODIES to the moiety that you do NOT have. So, everyone has the O moiety= not antibodies to O; type A make antibodies to type B, and vice versa. Type AB make no antibodies at all. Then lastly, there is a difference between red cells (packed cells) and plasma (where the antibodies are found). Cells alone with out plasma, have no antibodies, only antigens. See if that helps you answer the question.