Out of the following, which is a monomer?

Monomers are simple molecules that can link together to form more complex molecules. Lactose is a complex carbohydrate, so that's not it. RNA is a long chain of nucleotides, so that's not it. Deoxyribose is a monosaccharide in the nucleotides of DNA. It's part of a monomer, but not a monomer itself. Compound is way to broad of a term. Monomer is a subset of compound, so that's not it. Glycogen is a complex structure of glucose and protein, so that's not it. Amino Acids are a monomer that make up protein.