Hey There Jinny,
<span>What is the most important difference between vertebrates and invertebrates
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The primary difference between vertebrates and invertebrates is the presence of a backbone or spinal column, which vertebrates have and invertebrates do not. Examples of vertebrates are humans, dogs, cats and birds. Examples of invertebrates are flatworms, mollusks, sea urchins and insects.
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I'd say D but i'm not 100% sure
