Answer:
As I think the answer is C. Because the ideas about the models changed as more discoveries were made about the atom.
<span>The hydrogen-oxygen ratio is different.
Carbohydrates and lipids are macromolecules. These macromolecules or biomolecules help organisms to conduct and execute certain cellular activites making them alive and thrive in their certain environment. It is only that carbohydrates are more efficient at producing energy than lipids.</span>
The answer is B (speed up chemical reactions).