Hey there! :D
If you ever learned about protein synthesis, you probably have heard about how it is made with amino acids. Messenger RNA (a portion of DNA in the nucleus) is taken to the ribosomes (which make the protein) and the code from the DNA is converted to amino acid sequences, therefore, the polymer and correct answer is amino acid. These amino acids, all combined, become protein chains. I would encourage you to look into the process because it is very interesting and very helpful!
I hope this helps!
~kaikers
