One Function of Nucleotides Is Energy Transfer

One function of nucleotides is energy transfer. Carbohydrates can be used to store energy. These related processes are important because

A) if we could not store and transfer energy, we would have to match our energy input (eating) exactly to our energy requirements, even when sleeping.
B) there are not enough kinds of amino acids for proteins to be used as energy storage molecules.
C) energy transfer and storage are processes that are unique to humans, and therefore are used to determine the classification of people.
D) energy transfer is how we take the energy we gather from photosynthesis and transfer it into water molecules for later use when we need energy.