Answer: The correct answer is nucleotide.
Step-by-step explanation:
Nucleic acids are the polymer of nucleotides which are attached with each other with the help of phospho-diester bonds.
Nucleotide consists of sugar (ribose in RNA and deoxyribose in DNA), phosphate group, and nitrogenous base (A, T, G, and in DNA; and A, U, G, and C in RNA).