Here's why:

* Base pairs: The fundamental building blocks of DNA are nucleotides, each containing a base (adenine, guanine, cytosine, or thymine), a sugar, and a phosphate group. Base pairs are formed by complementary bases (adenine with thymine, guanine with cytosine).

* Ordered: The order of these base pairs is crucial. It determines the genetic information encoded by the DNA.

* Gene: A gene is a segment of DNA that contains the instructions for building a specific protein or functional RNA molecule.

Therefore, the sequence of base pairs along a gene constitutes the genetic code for that gene.