Answer:
Option A, pairs of nitrogen bases
Step-by-step explanation:
The helical structure of DNA if compared to the spiral staircase then, the following structure of spiral staircase will resemble to the following parts of DNA -
a) The spiral staircase's hand rail will be equivalent to the sugar phosphate base of DNA that holds the nitrogenous base
b) The steps of spiral case will be equivalent to the pair of nitrogenous base
Nitrogenous base pair include
- Pair of adenine (A) and thymine (T)
- Pair of guanine (G) and cytosine (C)
Thus, option A is correct