TOEFL Reading: ETS-TOEFL阅读机经 - 1VNFZ63TPK9W173XL$

According to paragraph 5, what was the main way that the earliest tetrapods differed from their immediate fish ancestors? A. The tetrapods had a different skeletal structure. B. The tetrapods had more sources of food available. C. The tetrapods had a circulation system. D. The tetrapods could move to new pools of water.