Explain why all single food items have more than one type of organic compound

Macromolecules are a set collection of polymers that composes most of the organic substances specifically in the organelles of cells. Thus, these organelles use lipids and proteins in doing cellular activity and keeps them functioning. Observe nitrogen and carbon, these two entities are called elements that are composed of atoms. Elements are the basic composition of a substance. Going back, examples of molecules could be nucleic tides, polypeptides, RNA, protein, lipids and etc.   

Protein
Carbohydrates
Lipids
Nucleic acids

The answer should be a