Amino acids are joined together by which kind of bond?

The correct answer is: peptide bond

A peptide bond is an amide type of covalent chemical bond. It is formed between two amino acids: C1 (carbon end) of one alpha-amino acid and N2 (nitrogen end) of another. Peptide bonds are the basis for the formation of a peptide chain and consequently protein.

Formation of peptide bond is a condensation process, meaning that when two amino acids combine and link, water molecule is released and dipeptide is a product of rection.