AIIMS 2019 Biology Nucleotides and Nucleic Acids MCQ Question

Option B is correct because adenylic acid (AMP), cytidilic acid (CMP), and guanylic acid (GMP) are all nucleotides, which consist of a nitrogenous base (adenine, cytosine, and guanine, respectively), a ribose sugar, and one or more phosphate groups. In contrast, option A includes cytosine, which is a nitrogenous base but not a nucleotide, while option C contains adenine, a base, and cytidine, which is a nucleoside, not a nucleotide. Option D includes uracil and thymidine, both of which are nucleosides, and thymidylic acid (TMP), which is a nucleotide, but the presence of the two nucleosides disqualifies the option. Understanding the distinction between nucleotides and nucleosides is crucial in molecular biology, as nucleotides are the building blocks of nucleic acids like DNA and RNA.