Which set of bases comprises the four chemicals found in DNA?

• A. Thymine, Adenine, Guanine, Cytosine
• B. Adenine, Cytosine, Uracil, Guanine
• C. Thymine, Cytosine, Guanine, Uracil
• D. Adenine, Uracil, Cytosine, Guanine

Answer: (A)

DNA is made from four bases: adenine, thymine, cytosine, and guanine. Thymine is a DNA-specific base (RNA uses uracil instead). So a correct set for DNA must include thymine and the other three canonical bases. The option that lists thymine along with adenine, cytosine, and guanine matches DNA’s four bases. The other options contain uracil or omit thymine, which would describe RNA or be incomplete for DNA.