b is the correct answer. hope this helps
Answer:
Most invertebrates (and higher animals) can be placed in one of two groups based on how they develop as embryos. The two groups are called protostomes and deuterostomes. ... It shows that echinoderms are more closely related to chordates than are the other invertebrate phyla. Explanation:
Carbon dioxide and methane.
The answer is A is you agree no problem im here to help if you disagree its ok i tried my best to help just saying