Which fins are paired in fishes?

The skin of a shark is covered with which type of scales?

Which of the following statements are not true about shark?
$a$. The skin is tough and covered with placoid scales
$b$. They possess a swim bladder which regulates buoyancy
$c$. The tail of shark is heterocercal
$d$. Ampulla of Lorenzini present in the snout of shark is a thermoreceptor.
$e$. It has five pairs of gill slits covered by operculum

Which of the following characteristic features always holds true for the corresponding group of animals?

Match the following:

Column-$I$	Column-$II$
$(1)$ $Scoliodon$	$(p)$ $Saw$ $fish$
$(2)$ $Pristis$	$(q)$ $Sting$ $ray$
$(3)$ $Carcharodon$	$(r)$ $Dog$ $fish$
$(4)$ $Trygon$	$(s)$ $Great$ $white$ $shark$

Which of the following structures form the copulatory organs in sharks and rays?