The answer is C
Why:
A - this is natural
B - water is natural
D - this is also natural
C- this is right because when we breathe out we produce more carbon dioxide then we breathed in.
173.99cm multiply 68.5 x 2.54 always use that number when converting inches to cm
Isn't a chemical change like something that's not a physical change or physically changed but is something that uses natural chemicals? that's my guess sorry if it's wrong I think I'm wrong though
