The nitrogenous base not present in DNA is

Uracil

The correct answer is Option (2) → Uracil

DNA contains adenine, guanine, cytosine, and thymine.

These bases pair specifically in the DNA double helix: Adenine pairs with Thymine through two hydrogen bonds, and Guanine pairs with Cytosine through three hydrogen bonds.

Uracil is not present in DNA.Instead, uracil is found in RNA (Ribonucleic Acid) where it replaces thymine. 
Thus, RNA contains: • Adenine • Uracil • Guanine • Cytosine

Therefore, the nitrogenous base that is not present in DNA is uracil.