A certain road accident patient with unknown blood group needs an immediate blood transfusion. A friend of his who is also a doctor at once offers his blood. What was the blood group of the donor?
Blood group O
The blood group was O. The person having O blood group is a universal donor. It lacks both antibodies 'a' and 'b' and thus will not cause agglutination or clumping of blood cells when transfused into a person with any of the four blood groups.