Answer:
C. both phosphate and sugar
Step-by-step explanation:
DNA is made up of two strands, each made of nucleotides. Each nucleotide, in turn, is composed of a sugar (deoxyribose), a phosphate group, and a nitrogenous base. There are four nitrogenous bases: adenine (A), thymine (T), cytosine (C), and guanine (G). DNA takes a double helix shape, like a spiral staircase where the sides are chains of sugars and phosphates connected by steps, which are the nitrogenous bases.