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.

• A
  $a, b, c$ and $e$
• B
  $b, c$ and $e$
• C
  $c, d$ and $e$
• D
  Only $e$