The $ABO$ blood grouping system was discovered by whom?

Blood does not clot inside the blood vessels due to the presence of

Detection of blood group is done by an agglutination test using antiserum. According to this:

Plasma is a straw-coloured,viscous fluid constituting nearly $A$ $\%$ of the blood,$B$ $\%$ of the plasma is water,and proteins constitute $C$ $\%$ of it. Choose the correct option for the blanks $A, B$,and $C$.

The blood of an anaemic person contains an unusually large number of immature nucleated $RBCs$. Which of the following would you suggest as a dietary supplement to improve his condition?

Which of the following conditions cause erythroblastosis foetalis?