In the context of the genetic code, which base does guanine pair with in DNA?

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

Answer: (D)

Verified step by step guidance

1. Recall the base pairing rules in DNA, which describe how nitrogenous bases pair with each other to form the double helix structure.
2. Understand that DNA bases are adenine (A), thymine (T), guanine (G), and cytosine (C).
3. Remember that adenine pairs with thymine via two hydrogen bonds, and guanine pairs with cytosine via three hydrogen bonds.
4. Note that uracil is not found in DNA; it replaces thymine in RNA and pairs with adenine there.
5. Therefore, guanine pairs specifically with cytosine in DNA according to the complementary base pairing rules.