Which fish gives birth to young ones?

Which of the following statements are not true?
$a$. Dermal scales of fishes form the exoskeleton.
$b$. Cycloid and ctenoid scales have distinct lines of growth which aid in determining the age of the fish.
$c$. Fish scales are never shed.
$d$. The skin in elasmobranchs is covered with placoid scales.
$e$. The development of a placoid scale is not like the development of a tooth.

Which one of the following is a cartilaginous fish?

Presence of claspers is an important character in

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

Which of the following structures is not associated with fish scales?