Which blood type is described as lacking both A and B antigens?

• A. Type O blood
• B. Type AB blood
• C. Type A blood
• D. Type B blood

Answer: (A)

ABO typing is based on whether A or B antigens appear on the surface of red blood cells. If neither A nor B antigen is present, the blood type is O. This is why the description fits Type O: it lacks both A and B antigens. People with this type have anti-A and anti-B antibodies in their plasma, which is why O red blood cells can be given to anyone (no A or B antigens to trigger a reaction), while they must receive compatible blood to avoid their antibodies attacking donor cells.