Question

Which are primitive vertebrates?
a. Cnidoblasts
b. Bilateral symmetry
c. Gill opening d. Body scales​

Answer 1

Answer:

A vertebrate is an animal that has a backbone and a skeleton. Vertebrate animals include humans. When you think about vertebrates, think about bones: this word has to do with animals that have a lot of bones, in the form of a skeleton. ... Animals without a backbone are called invertebrates.

Gill opening is you correct answer dude!

Explanation:

hope it will help you