In DNA structure, which nitrogenous base forms complementary base-pairing with cytosine (C)?

• A. Uracil (U)
• B. Guanine (G)
• C. Thymine (T)
• D. Adenine (A)

Answer: (B)

Verified step by step guidance

1. Recall the base-pairing rules in DNA, which state that specific nitrogenous bases pair with each other through hydrogen bonds.
2. Identify that cytosine (C) is a pyrimidine base, and in DNA, it pairs with a purine base.
3. Remember that in DNA, cytosine (C) pairs specifically with guanine (G) through three hydrogen bonds.
4. Note that thymine (T) pairs with adenine (A), and uracil (U) is found in RNA, not DNA.
5. Conclude that the complementary base to cytosine (C) in DNA is guanine (G).