<span>an animal whose mouth develops from a second opening in the early embryo, opposite to the initial opening blastopore of the rudimentary gut. Chordates and echinoderms are deuterostomes.</span>
It is only because of their life spand... its pretty short.
Oxygen is the answer for this question.
That Jupiter, Saturn, Uranus, and Neptune are the outer planets and the other planets are the 4 inner planets.
C because you have to have genetic material .
