Answer: The steps are made of nitrogenous bases; deoxyribose sugars linked with phosphates.
Explanation: The rungs of the DNA are made of nitogenous bases (The nitrogenous bases are adenine (A), thymine (T), guanine (G) and cytosine (C) ) they are held together by weak hydrogen bonds.
The railings of the DNA are made of deoxyribose sugars which are alternating with phosphates. This part of the molecule is referred to as the "backbone".