One of the factors required for the maturation of erythrocytes is

Which blood group$(s)$ can be safely transfused to a person with blood group $A$?

Which of the following is known as the graveyard of red blood cells $(RBCs)$?

Arrange the following formed elements in the decreasing order of their abundance in blood in humans :
$(a)$ Platelets
$(b)$ Neutrophils
$(c)$ Erythrocytes
$(d)$ Eosinophils
$(e)$ Monocytes
Choose the most appropriate answer from the options given below :

In humans,the normal blood pressure is maintained by the blood protein called

Match the type of blood cells in Column $I$ with their respective structure in Column $II$ and function in Column $III$ and select the correct option given below.

Column $I$	Column $II$ $\&$ $III$
$I$. Erythrocytes	$D$. Enucleated,biconcave circular in shape; $N$. Transport of gases $O_2$ and $CO_2$.
$II$. Neutrophils	$A$. Spherical large cells,nucleus with many lobes; $O$. Phagocytic in function.
$III$. Lymphocytes	$C$. Spherical nucleus,agranular cytoplasm; $M$. Humoral and cell-mediated immunity.
$IV$. Thrombocytes	$B$. Cellular fragments small,oval shaped; $L$. Clotting of blood.