Question

Which statement is true regarding the relationship between vertebrates and chordates?

Answer 1

Ans.  

All vertebrates are chordates, but not all chordates are vertebrates. Both vertebrates and chordates show presence of pharyngeal gill slits, a nerve cord, and a post-anall tail in some stages of their life. However, all vertebrates have a vertebral column, developed from notochord present in embryonic stage, while vertebral column is absent in some chordates.  

Thus, the correct answer is option). 'All vertebrates are chordates.'

Answer 2

The answer is all vertebrates are chordates, but not all chordates are vertebrates.
Why? because a vertebrate is just a kind of chordate. Vertebrates develops on the chordate but not all chordates develop between vertebrates.