Final answer:
The shape of the DNA molecule is referred to as the double helix, which resembles a spiral staircase with the sides being the sugar-phosphate backbone and the steps being the base pairs.
Step-by-step explanation:
The correct answer to the question is a) the double helix.
The structure of DNA consists of two long strands or polymers of nucleotides that twist around each other, giving the shape that is referred to as a double helix. This is similar to a spiral staircase, where the sides of the staircase represent the sugar-phosphate backbone, and the steps or rungs represent the base pairs of nucleotides. Specifically, these base pairs are adenine (A), which always pairs with thymine (T), and guanine (G), which always pairs with cytosine (C), creating the familiar structure that is integral to replicating and passing on genetic information.