Answer:
The correct answer will be option-B (purine).
Explanation:
Nucleic acid structure is made up of monomer unit called nucleotide. Each nucleotide is composed of a five-carbon sugar, a phosphate group and five types of nitrogenous bases.
The nitrogenous bases are categorized in two forms the purines (adenine and guanine ) and the pyrimidines (cytosine, thymine and uracil). The "purines" contain double rings in their structure due to which they appear larger in size than pyrimidines which are made up of single rings.
Thus, Option-B is the correct answer.
I think it’s B having second thoughts
Nitrogen is the most important component of DNA, protein, enzymes etc. Its recycling in the atmosphere is necessary, beacuse free nitrogen in the atmosphere balance the atmosphere composition. In soil it is important for fertility needed for plant growth. In heterotrophs it is an essential component of organic compounds.