Q: Fact 1: Amphibians are the first true tetrapods, or vertebrates with four limbs. Fact 2: Animals with backbones are called vertebrates. Given the two facts above, amphibians are the first true what with four limbs?

pick from the following. a. members of their own species b. to move people c. warm-blooded d. Due to their feet e. animals with backbones f. remains of prehistoric life g. Something to move h. Generating heat
The answer is:
e.