Answer:
Thymine and Cytosine
Step-by-step explanation:
Genes are stored within DNA or deoxyribonucleic acids- these are long-chain, macromolecules that form a double helix. They are made up of nucleotides, special monomers made up of nucleotides comprise, 5-Carbon deoxyribose sugar, a nitrogenous base (adenine, guanine thymine, and cytosine) and a phosphate group.
The nitrogenous bases pair up via hydrogen bonding. The pyrimidine bases include cytosine and thymine. In base-pair formation, Adenine forms double bonds with thymine, and cytosine bonds with guanine. These pyrimidines are 6 carbon ringed molecules that contain a double bond.