Which of the following is not a characteristic of chordates?

Which of the following animals is not a vertebrate?

The following are the statements about non-chordates:
$A$. Pharynx is perforated by gill slits.
$B$. Notochord is absent.
$C$. Central nervous system is dorsal.
$D$. Heart is dorsal if present.
$E$. Post anal tail is absent.
Choose the most appropriate answer from the options given below:

Post-anal tail is present in

$A$ common characteristic of all vertebrates is $..........$

The notochord is .........