The excretory structure of $Amphioxus$ $(Cephalochordate)$ is:

The nephrostomes,in the kidneys,are functional in

Match the excretory organs listed under column $I$ with the animals given under column $II$. Choose the answer which gives the correct combination of alphabets of the two columns.

Column $I$ (Excretory organs)	Column $II$ (Animals)
$A$. Nephridia	$p$. Hydra
$B$. Malpighian tubules	$q$. Leech
$C$. Protonephridia	$r$. Shark
$D$. Kidneys	$s$. Round worms,$t$. Cockroach

The $Wolffian$ body is also known as:

Urinary bladder is absent in:

$Assertion (S)$: In $Paramecium$,the contractile vacuole performs excretion.
$Reason (R)$: In $Planaria$,flame cells are present,which perform excretion.