Answer:
The base pairs are what makes up an individual's genes.
Check below for further explanation.
Step-by-step explanation:
The base pairs A, C, T and G are the basic molecules which makes is the DNA of individual.
The genes of an individual which determines the phenotypical expressions found in an individual such as eye colour, height, etc, are functional units found in the DNA.
Therefore, the arrangement of the base pairs determines the gene present in an individual and thus, the individual's phenotype.