The following structure is of

Correct option is B

The correct answer is (b) Uracil
Explanation: • The image displays the chemical structure of Uracil, which is one of the four nucleobases in the nucleic acid of RNA (Ribonucleic Acid). • It is a pyrimidine derivative, characterized by a single six-membered heterocyclic ring containing two nitrogen atoms at the 1 and 3 positions. • Chemically, it is known as 2,4-dioxopyrimidine because it features two carbonyl (oxo) groups at the C-2 and C-4 positions. • In the RNA structure, Uracil forms two hydrogen bonds with Adenine during the process of base pairing. • It is typically absent in DNA, where its functional role is replaced by Thymine.
Information Booster: • Thymine is essentially a "methylated" version of Uracil; the presence of the methyl group in DNA helps the cell distinguish between natural bases and damaged bases (like deaminated cytosine). • In laboratory settings, Uracil is used as a biochemical marker to help scientists track the synthesis and degradation of RNA in living organisms.
Additional Knowledge:
Adenine (Option a) • Unlike the single-ring pyrimidines, Adenine is a purine base with a double-ring structure (a fused pyrimidine-imidazole ring system). • It is found in both DNA and RNA and is a key component of ATP (Adenosine Triphosphate).
Thymine (Option c) • Its structure is almost identical to Uracil but contains an additional methyl group (CH3) at the C-5 position. • For this reason, it is chemically referred to as 5-methyluracil.
Cytosine (Option d) • This is also a pyrimidine base, but instead of two carbonyl groups, it has an amine group (NH2) at the C-4 position. • It pairs with Guanine through three hydrogen bonds in both DNA and RNA.