Give the origin of Red blood cells.

Grouping of $ABO$ blood is based on the

With reference to the blood in a normal person,which one of the following statements is correct?

In which of the following pairs does erythroblastosis fetalis occur?

Who was the scientist to introduce $ABO$ blood groups?

$A$ woman of blood group $O$ presented a baby of blood group $O$ which she claimed as her child. She brought a suit against a man of $AB$ blood group as the father of the child. Which statement is correct as per your judgement?