$A$ person injured in a road accident does not have a known blood group and requires an immediate blood transfusion. $A$ doctor friend offers to donate blood immediately. What would be the blood group of this doctor?

Diapedesis is the characteristic feature of

Which are the main blood groups found in humans on the basis of antibodies and antigens?

Cyanocobalamine is essential for the formation of

Cells produced in the bone marrow include .......

Select the incorrect statements with reference to $Rh$ grouping.
$A$. Erythroblastosis foetalis is a condition observed having foetus with $Rh^{+ve}$ blood and mother with $Rh^{+ve}$ blood.
$B$. $Rh$ antigen is observed on $RBCs$ in the majority of human beings.
$C$. Before blood transfusion,$Rh$ group should also be matched.
$D$. $Rh$ incompatibility is observed when a pregnant mother is $Rh^{-ve}$ and the foetus is $Rh^{+ve}$.
$E$. Erythroblastosis foetalis can be avoided by administering anti-$Rh$ antibodies to the mother immediately after the delivery of the second child.
Choose the answer from the options given below: