Answer:
B. An Ecosystem
Explanation:
A C and D do not fit the picture.
Plants use carbon to live, just like humans use oxygen. It's a virtuous cycle sine humans breathe oxygen and expel carbon, and plants "breathe" carbon and expel oxygen.
If plants weren't there to "breathe" the carbon, it would just sit in the world, and build up in the atmosphere.
<span>Alveolar sacs are the part of the respiratory system where the exchange of air happens.
Inhalation is the
process where oxygen is taking in to the respiratory system thru the
nasal passageways and to the tiny alveolar sacs of the lungs. This
process also expands the lungs and the diaphragm heightens or elevates
upward.
The counterpart of inhalation is exhalation, where the
carbon dioxide is taken out of the lungs in opposite of the oxygen
passageways.
This two exchange is called the gas exchange or
respiration which happens in the respiratory system responsible for
enabling and providing oxygen throughout the body. </span>