Which is the primary cation present in the blood plasma?

Assertion: The regulation of $RBC$ production is accomplished by $FSH$.
Reason: Erythropoietin hormone circulates to red bone marrow where it increases stem cell mitosis and speeds up the development of $RBCs$.

Match the following columns:

Column-$I$ (Cells)	Column-$II$ (Average number per $mm^3$)
$P$. Erythrocytes	$I$. $1.5$ to $3.5$ Lakhs
$Q$. Leukocytes	$II$. $6,000$ to $8,000$
$R$. Thrombocytes	$III$. $5$ to $5.5$ Million

In rabbit,the function of the spleen is

You are required to draw blood from a patient and to keep it in a test tube for the analysis of blood corpuscles and plasma. You are provided with the following four types of test tubes. Which of them will you $NOT$ use for this purpose?

$RBCs$ have an average life span of (in $days$)