What do chains of amino acids build?

Proteins

Explanation:

Chains of amino acids linked together by peptide bonds form proteins. The properties of the amino acids in the chain dictates the complex structure and function of proteins, including folding, enzymatic activity, and binding sites.

The order of amino acids in the chain is dictated by DNA via the transcription of an intermediate molecule of mRNA, which is then translated into a sequence of amino acids.

fumikage isn't really a bird, and tsuyu does have teeth. tsuyu has a transformation quirk which still allows her to be partially human. otherwise we'd have a large frog running around. fumikage has teeth because again, he isn't a bird. his head was a quirk mixture if i'm correct.

your answer would be a, maximum exploitation of resources.