Final answer:
The backbone of DNA consists of a pentose sugar and a phosphate group, which is answer (C) I and II Only. Nitrogenous bases are important but are not part of the backbone itself.
Step-by-step explanation:
The backbone of DNA is made up of two essential components: a sugar and a phosphate group. These two elements, a pentose sugar and a phosphate group, alternate to form the structure upon which the nitrogenous bases attach, but it is specifically the sugar and phosphate that make up the backbone itself. The correct answer to the question is (C) I and II Only, meaning the backbone of DNA consists of both sugar and phosphate. While nitrogenous bases are a critical part of the DNA structure, they are not part of the backbone; instead, they attach to the sugars and pair with bases from another DNA strand to form the double helical structure.
The backbone of DNA is made up of three components: sugar, phosphate, and nitrogenous bases. Each nucleotide, which is the building block of DNA, consists of these three components. The sugar and phosphate group form the backbone of the DNA molecule, while the nitrogenous bases project outwards from the backbone. The nitrogenous bases in DNA are adenine (A), cytosine (C), guanine (G), and thymine (T).