Honestly I don't know if this is completely right but my best guess would be a registered nurse..
Answer:
A. Negative feedback mechanism
Answer:
thank you for the points
Explanation:
if you don't mind can you also mark me brainliest. :)
Answer:
The baby starts breathing
Explanation:
While in the womb, a fetus has its oxygen delivered to it, and the waste products removed (all via the mother's bloodstream), so there is no reason to separate all the chambers of the heart while still in the womb.
However, once the baby is born and it is breathing, the chambers need to differentiate in order to allow the blood to reach the lungs, and the oxygenated blood and deoxygenated blood do not mix.