What are vertebrates
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Explanation:

an animal of a large group distinguished by the possession of a backbone or spinal column, including mammals, birds, reptiles, amphibians, and fishes.

The six classes of vertebrates found in Iowa are lampreys, ray-finned fishes, amphibians, reptiles, birds, and mammals. The central nervous system, and the vertebrae that support it and the rest of the body in these animals, sets them apart from invertebrate animals

i think it's c