Which is the best definition of metabolism?
a. series of chemical reactions necessary for the use of the raw material.
b. releases energy that is eventually converted into atp
c. building of a large protein from individuals amino acids.
d. breakdown of a large protein into individual amino acids.

a. series of chemical reactions necessary for the use of the raw material.  

Explanation:

The term metabolism is used to describe the various chemical reactions in the body that meet the structural and energy needs of a living being.  Among the purposes of these chemical reactions, we can mention the synthesis and breakdown of biomolecules, energy production and the conversion of nutrient molecules into macromolecule precursor units.

Metabolism is not unique to humans and occurs in all living beings, whether unicellular or multicellular. The reactions that make up metabolism can be classified into two major metabolic processes: anabolism and catabolism.