Which structural feature is shared by both DNA and RNA molecules?

• A. They both contain the nitrogenous base thymine.
• B. They both have deoxyribose as their sugar.
• C. They both contain a phosphate backbone.
• D. They are both typically double-stranded.

Answer: (C)

Verified step by step guidance

1. Identify the main structural components of nucleic acids: sugar, phosphate group, and nitrogenous bases.
2. Recall that DNA contains deoxyribose sugar, while RNA contains ribose sugar, so they do not share the same sugar.
3. Remember that thymine is a nitrogenous base found only in DNA; RNA contains uracil instead of thymine.
4. Understand that both DNA and RNA have a backbone made of alternating sugar and phosphate groups, which is called the phosphate backbone.
5. Note that DNA is typically double-stranded, whereas RNA is usually single-stranded, so this feature is not shared.