Give an example of the following:
$(a)$ Roundworm
$(b)$ Fish possessing poison sting
$(c)$ $A$ limbless reptile/amphibian
$(d)$ An oviparous mammal

Consider the following features:
$(a)$ Organ system level of organisation
$(b)$ Bilateral symmetry
$(c)$ True coelomates with segmentation of body
Select the correct option of animal groups which possess all the above characteristics.

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

Column $X$	Column $Y$
$(1)$ Skin without scales	$(P)$ Catla
$(2)$ Placoid scales	$(Q)$ Hagfish
$(3)$ Cycloid scales	$(R)$ Chameleon
$(4)$ Epidermal scales	$(S)$ Ray-fish

Choose the correct statement.

Flatworms and roundworms are respectively called ........

Trochophore larva occurs in