Which of the following is a difference between DNA and RNA?

• A. RNA uses deoxyribose and thymine
• B. RNA uses ribose and uracil
• C. RNA is double-stranded
• D. DNA uses ribose and thymine

Answer: (B)

The main concept being tested is how the sugars and bases differ between DNA and RNA. RNA uses ribose as its sugar, which has a hydroxyl group at the 2' position, and it contains uracil instead of thymine. DNA, on the other hand, uses deoxyribose (lacking the 2' OH) and thymine. These two differences—ribose with uracil for RNA versus deoxyribose with thymine for DNA—define the distinct identities and properties of the two nucleic acids. This is why the correct statement is that RNA uses ribose and uracil. The other options mix up the sugar or the base in a way that describes DNA rather than RNA, or incorrectly describe RNA as double-stranded.