$A$ shell,as a body covering,is not present in which of the following?

Fill in the blanks marked in the classification table of $Vertebrata$ from the choices provided below with respect to $A, B, C, D, E$ and $F$ and choose the correct option:
$I$. Pisces
$II$. Osteichthyes
$III$. Agnatha
$IV$. Gnathostomata
$V$. Chondrichthyes
$VI$. Cyclostomata
$A - B - C - D - E - F$

What is common among bed bugs,leeches,and mosquitoes?

Match the following list of animals with their level of organisation and choose the correct sequence.

Column $I$	Column $II$
$A$. Organ level	$p$. Pheretima
$B$. Cellular aggregate level	$q$. Fasciola
$C$. Tissue level	$r$. Spongilla
$D$. Organ system level	$s$. Obelia

Match the following columns:

Column-$I$	Column-$II$
$I$. Choanocytes	$p$. Cnidaria
$II$. Cnidoblasts	$q$. Platyhelminthes
$III$. Flame cells	$r$. Porifera
	$s$. Aschelminthes

Select the correct match for $X$ and $Y$:

Column $X$	Column $Y$
$(1)$ Platyhelminthes	$(P)$ Malpighian tubules
$(2)$ Aschelminthes	$(Q)$ Nephridia
$(3)$ Arthropoda	$(R)$ Flame cells
$(4)$ Annelida	$(S)$ Renette cells