Nucleic acids are a polymer of nucleotide monomeric units. Each nucleotide consists of

The correct option/answer is base-sugar-phosphate.

Nucleic acids (such as DNA and RNA) are polymers made up of repeating monomeric units called nucleotides. Each individual nucleotide is composed of three distinct chemical components linked together:
1. A Nitrogenous Base: A nitrogen-containing ring structure that can be a purine (adenine or guanine) or a pyrimidine (cytosine, thymine, or uracil).
2. A Pentose Sugar: A five-carbon sugar molecule, which is ribose in RNA and deoxyribose in DNA.
3. A Phosphate Group: A phosphorus atom bonded to four oxygen atoms, which links the sugars of adjacent nucleotides to form the sugar-phosphate backbone of the nucleic acid chain.

When a nitrogenous base is attached to a pentose sugar without the phosphate group, the molecule is known as a nucleoside. The addition of a phosphate group to the nucleoside completes the structure, forming a nucleotide. Therefore, a nucleotide consists of a base, a sugar, and a phosphate group.