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

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