Which of the following base is not present in DNA?

Uracil

The correct answer is Option (4) → Uracil

DNA (deoxyribonucleic acid) contains four nucleotide bases:

• Purines: Adenine (A), Guanine (G)
• Pyrimidines: Cytosine (C), Thymine (T)

Uracil (U) is a pyrimidine base found in RNA (ribonucleic acid), where it pairs with adenine (A-U). In DNA, thymine (T) replaces uracil and pairs with adenine (A-T). This difference helps distinguish DNA from RNA and provides DNA with greater stability (thymine is more resistant to deamination).

Thus, the base not present in DNA is Uracil.