Answer the following question given this paragraph: 

Vertebrates evolved from primitive chordates. This occurred about 550 million years ago. The earliest vertebrates may have been jawless fish, like the hagfish in Figure below . Vertebrates evolved a backbone to replace the notochord after the embryo stage. They also evolved a cranium , or bony skull, to enclose and protect the brain.


Q: Vertebrates evolved from primitive forms of which creature?

 Choices:

- arthropods

- humanoids

- cephalopods

- chordates

A:
chordates
