The correct answer is D. O.
Blood group O is the universal donor because it does not have any A or B antigens on the surface of the red blood cells. This means that it can be donated to people with any blood type, regardless of their own blood type.
Blood group A has A antigens on the surface of the red blood cells. People with blood type A can only receive blood from people with blood type A or AB.
Blood group B has B antigens on the surface of the red blood cells. People with blood type B can only receive blood from people with blood type B or AB.
Blood group AB has both A and B antigens on the surface of the red blood cells. People with blood type AB can only receive blood from people with blood type AB.
It is important to note that blood type is determined by the presence or absence of certain antigens on the surface of red blood cells. Antigens are proteins that the body’s immune system can recognize. If a person receives blood that contains antigens that their body does not recognize, their immune system will attack the blood cells, which can lead to serious health problems.
For this reason, it is important to only receive blood from a donor with the same blood type.