Answer:a;nucleotide
Explanation:a nucleotide is the building block of the Nucleic Acids. It forms the component part of the nucleic acids.A nucleotide usually contains a nitogeneous base, a five carbon sugar and phosphate group.
Nucleic acids may be ribonucleic acid RNA or deoxyribonucleic acid DNA. Nucleic acids functions to carry information which directs the synthesis of proteins and transmits genetic information.
However RNA and DNA can be differentiated based on the pentose sugar they contain.RNA contains a ribose sugar and DNA contains a deoxyribose sugar, due to the removal of an oxygen atom.
Nucleotide may undergo condensation to form polynucleotide