Answer:
Carbohydrates, or polysaccharides, contain carbon, hydrogen, and oxygen. Their monomer, or building block, is a monosaccharide/simple sugar.
Proteins contain carbon, hydrogen, oxygen, and nitrogen. Their monomer, or building block, is an amino acid. Remember, these amino acids are connected by peptide bonds to form proteins.
Nucleic acids contain carbon, hydrogen, oxygen, nitrogen, and phosphorus. Their monomer, or building block, is a nucleotide—formed of a pentose sugar, phosphate group, and a nitrogenous base (adenine, cytosine, guanine, and thymine).