The volume of the filtrate per day is $X$ liters and the volume of urine released per day is $Y$ liters. It means about $Z$ $\%$ of the filtrate is reabsorbed by the process of reabsorption.

All of the following processes are performed in a nephron,except:

Match the items in Column-$I$ with those in Column-$II$.

Column-$I$	Column-$II$
$(a)$ Podocytes	$(i)$ Crystallised oxalates
$(b)$ Protonephridia	$(ii)$ Annelids
$(c)$ Nephridia	$(iii)$ Amphioxus
$(d)$ Renal calculi	$(iv)$ Filtration slits

Select the correct option from the following:

Identify the true statements and choose the correct option accordingly.
$I.$ Blood vessel leading to the glomerulus is called efferent arteriole.
$II.$ Vasa-recta,peritubular capillaries and glomerulus,all have blood.
$III.$ Cortical nephrons have highly reduced vasa-recta.
$IV.$ Vasa-recta runs parallel to the Henle's loop in the juxta-medullary nephron.

The primary function of the kidney is ........ .

Assertion : Secreting hypotonic urine is effective in reducing urinary loss of water.
Reason : Hypotonic urine is more concentrated and higher in osmotic pressure than the blood.