Which nitrogenous base is not found in DNA?

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

Answer: (B)

Verified step by step guidance

1. Recall the four nitrogenous bases found in DNA: adenine (A), guanine (G), cytosine (C), and thymine (T).
2. Understand that DNA is composed of these four bases, which pair specifically: adenine pairs with thymine, and guanine pairs with cytosine.
3. Recognize that uracil (U) is a nitrogenous base found in RNA, not DNA.
4. Note that uracil replaces thymine in RNA, pairing with adenine during RNA transcription.
5. Therefore, identify uracil as the nitrogenous base that is not found in DNA.