Yes we never know what could happen in an eco system
It should be C. It is very literal, but I think C
Well, carbohydrates burn and release energy. Nucleic acids give identity (like DNA, RNA). Lipids also give energy, but it's more difficult (they must be first turned into carbohydrates first). Proteins are building blocks for the cells.
Now, knowing all of this should make it easy to choose the correct answer :)
