Which organ is known as the 'graveyard of red blood cells'?

What is the full form of $PMNL$?

The medium of plasma is

In a normal healthy person,if the total number of $WBCs$ is about $9000 / mm^3$,then the number of Agranulocytes is about . . . . . . $/ mm^3$ of blood.

Biological marriage of one of the following should be avoided:

Choose the incorrect sentence$(s)$.
$(I)$ $RBCs$ are formed in the white bone marrow in adults.
$(II)$ $RBCs$ have a red colour because of the presence of a protein called haemoglobin.
$(III)$ The nucleus is present in $RBCs$ in most mammals,and they are biconcave in shape.
$(IV)$ $A$ healthy individual has $12-16 \, g$ of haemoglobin in every $100 \, ml$ of blood.