AIIMS 2017 Chemistry Nucleic Acids MCQ Question

Option B is correct because uracil (U) is a pyrimidine nitrogenous base found in RNA, which replaces thymine (T) found in DNA. Uracil consists of a six-membered ring containing two nitrogen atoms and four carbon atoms, with the molecular formula C₄H₄N₂O₂. Other options are not relevant as they do not provide information about uracil's structure or its role in RNA, making them incorrect in the context of the question. Understanding the distinct bases in RNA and DNA is crucial for grasping the differences in their molecular composition and function.