Your answer would A insects because insects are the only invertebrates that can maintain flight. FOr example Butterflies and Flies Can maintain flight
Hope this has helped :)<span />
The answer is <span>Topoisomerase.
Topoisomerase is an enzyme responsible for twisting of DNA helix. After DNA strand is untwisted by helicase enzyme, DNA must be twisted again so the normal function of DNA can be sustained. If left untwisted, the replication fork will continue to grow, the normal function of DNA will stop.</span>
The organ that living things such as fish use to extract dissolved oxygen from water are the gills. As land animals and humans don't have gills, we can't breath underwater and take in the oxygen from that source.
I am not that good, but maybe the digestive system
