Which base pairs with $U\left(\mathrm{uracil}\right)$ in $\mathrm{RNA}$?

• A. $\mathrm{Cytosine}$
• B. $\mathrm{Uracil}$
• C. $\mathrm{Guanine}$
• D. $\mathrm{Adenine}$

Answer: (B)

Verified step by step guidance

1. Understand that RNA is a nucleic acid similar to DNA, but it contains the base uracil (U) instead of thymine (T).
2. Recall the base pairing rules for RNA, which are similar to those for DNA, but with uracil pairing instead of thymine.
3. In RNA, adenine (A) pairs with uracil (U) through hydrogen bonding.
4. Recognize that cytosine (C) pairs with guanine (G) in both DNA and RNA.
5. Conclude that in RNA, uracil (U) pairs with adenine (A), not cytosine (C) or guanine (G).