Answer:
The answer is autotrophs
Explanation:
During the early days of the Earths life there was no oxygen but there was plenty of CO2 which the autotrophs took and used as food while discarding the excess which was the oxygen.
Tachypnea, frequent desaturations, Tachycardia, retractions, nasal flaring, grunting, and etc.<span>
</span>
