Final answer:
Type O negative blood is the universal donor because it lacks A and B antigens that could trigger an immune response. AB+ is the universal recipient, not the universal donor, which is a common misunderstanding.
Step-by-step explanation:
Blood Type and Universal Donor
The question pertains to which blood type is considered the universal donor. The universal donor blood type is Type O negative. It's important to note that this blood type has neither A nor B antigens on the surface of the red blood cells. Because of the absence of these antigens, Type O negative blood does not elicit an immune response when transfused into a person of any other blood type.
Contrary to Type O negative, Type AB positive is known as the universal recipient, capable of receiving blood from any blood type due to the presence of both A and B antigens and no anti-A or anti-B antibodies in the plasma. The discovery of the ABO blood groups by Karl Landsteiner significantly advanced our understanding of blood type compatibility for transfusions. Therefore, for the universal donor question, Type O negative is the correct answer, not AB-, which is a common misconception.