Answer:
The correct answer would sugar and phosphate.
The nucleotide consists of three units; sugar (ribose in RNA and deoxyribose in DNA), a phosphate group, and a nitrogenous base (adenine, guanine, cytosine, thymine, or uracil).
The sugar group of one nucleotide is attached to sugar of another nucleotide with the help of phosphodiester bond.
Thus, alternate sugar and phosphate groups form the backbone of nucleic acid from which nitrogenous bases stick out.