Which of the following is a major difference between $\mathrm{RNA}$ and $\mathrm{DNA}$?

• A. $\mathrm{RNA}$ is double-stranded while $\mathrm{DNA}$ is single-stranded.
• B. $\mathrm{RNA}$ contains uracil instead of thymine.
• C. $\mathrm{RNA}$ has a deoxyribose sugar while $\mathrm{DNA}$ has a ribose sugar.
• D. $\mathrm{RNA}$ is more stable than $\mathrm{DNA}$ under alkaline conditions.

Answer: (B)

Verified step by step guidance

1. Identify the structural components of RNA and DNA. RNA contains ribose sugar, while DNA contains deoxyribose sugar.
2. Examine the nitrogenous bases present in RNA and DNA. RNA contains uracil, whereas DNA contains thymine.
3. Consider the stability of RNA and DNA under different conditions. RNA is generally less stable than DNA under alkaline conditions due to the presence of the 2'-hydroxyl group in ribose.
4. Analyze the strand structure of RNA and DNA. RNA is typically single-stranded, while DNA is double-stranded.
5. Compare the key differences between RNA and DNA based on the above observations to determine the major difference.