The most primitive vertebrates are ____.

A) jawless fishes
B) amphibians
C) cartilaginous fish
D) birds
E) bony fish

Jawless Fishes

A group of fish characterized by their lack of a true jaw, examples include lampreys and hagfishes.

Primitive Vertebrates

Early forms of vertebrates, such as fish and amphibians, that show basic features of the vertebrate lineage and provide insight into evolutionary history.

Cartilaginous Fish

Cartilaginous fish are a class of fishes that have skeletons made entirely out of cartilage, rather than bone, including sharks, rays, and skates.