Answer
B
Work Step by Step
Option A is incorrect. Sponges are not chordates.
Option C is incorrect. Fishes are vertebrate chordates.
If options A and C are incorrect, that means option D is also incorrect.
Option B is correct. Only two types of chordates are nonvertebrates, meaning they do not possess backbones. These two chordates are tunicates and lancelets.