I’d say it’s alveoli because across which diffusion occurs and they’re elastic so they can adjust to different pressures of gases within the lungs...
The answer is carbon, hoped this helps you!
Option C - They show that the number of atoms of each element is the same in the products and reactants.
The conservation of mass essentially states that no matter can be created or destroyed. It is because of the conservation of mass that we have to balance chemical equations in order to ensure than no atoms are destroyed or created.
-T.B.
