Respiratory organs in aquatic arthropods like crayfish,prawn and molluscs like $Unio$ are

$A$ : The lungs of birds are provided with air sacs.
$R$ : Air sacs supplement respiration.

In the lower order of invertebrate animals,how does the respiration process take place?

In crustaceans,respiration occurs through ..........

Which animal has unpaired lungs?

Choose the correct option by matching the organisms in Column-$I$ with their respective respiratory organs in Column-$II$.

Column-$I$	Column-$II$
$(p)$ Sponges	$(I)$ Through tracheal tubes
$(q)$ Insects	$(II)$ Through lungs
$(r)$ Molluscs	$(III)$ Vascularized gills
$(s)$ Reptiles	$(IV)$ Simple diffusion over their entire body surface
	$(V)$ By their moist cuticle

Find the correct sequence for $p-q-r-s$.