A D
A B
C D
B C
Correct option is A. A BNucleotides are organic molecules that serve as the monomer units for forming the nucleic acid polymers deoxyribonucleic acid and ribonucleic acid, both of which are essential biomolecules within all life-forms on Earth.The nucleotide is a compound consisting of a nucleoside linked to a phosphate group.Nucleotides form the basic structural unit of nucleic acids such as DNA.Hence. A B two are nucleotides.So, the correct answer is 'A B'