Final answer:
The observation that would provide the strongest evidence for the macromolecule being involved in the storage of energy is that all of the monomers are identical and composed only of carbon, oxygen, and hydrogen.
Step-by-step explanation:
The observation that would provide the strongest evidence for the macromolecule being involved in the storage of energy is option A. All of the monomers being identical, composed only of carbon, oxygen, and hydrogen. This is because carbohydrates are the macromolecules that primarily store energy in cells, and they are made up of carbon, oxygen, and hydrogen.