Name the blood cells whose reduced count causes excessive loss of blood from the body due to a defect in the blood clotting process.

Explain the process of coagulation of blood.

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:

Which test tube from the given options is $NOT$ used for keeping blood in a non-coagulated state for the analysis of blood corpuscles?

Which of the following cells secrete substances like histamine,serotonin,and heparin?

$A$ person with an unknown blood group ($ABO$ system) has lost a large amount of blood in an accident and needs an immediate blood transfusion. $A$ friend of the person has a valid certificate of their own blood group and is ready to donate blood without delay. What could be the blood group of the donor friend?