Which one of the following is not a characteristic feature of all the chordates?

What are the general characteristics of the subphylum Vertebrata?

Which one of the following features are true for chordates?
$(a)$ Heart is ventral.
$(b)$ Pharyngeal gill slits present.
$(c)$ Central nervous system is ventral,solid and single.
$(d)$ Post-anal tail is present.
$(e)$ Notochord is present.
Choose the most appropriate answer from the options given below:

Fishes,amphibians,reptiles,and birds are kept in the same

The body is divided into head and trunk in:

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