Your answer would be organism/organelle
B. An oak tree grows from the seed material in an acorn
I believe the correct answer from the choices listed above is option C. It is the products that is not requires in a chemical reaction. These are the substances that is being produced from the reactants involved in the system which needs the atomic nuclei and energy.
I believe it is (B) It is not used up
Hope this helps!
- Rainbow :3