At what level does gene variability quantify genetic variation?

Answer is whole-gene or whole-genome.

Explanation:

Genetic variation explains that, no matter how related or identical some organisms might be, there is a or some characters that make them different from one another. These difference is referred to as variation.

Furthermore, whole-gene means the coding and non-coding regions of the DNA>

There are some activities or occurrences that cause genetic variation, these are gene flow, mutation and sexual reproduction.

Examples of genetic variation are color of the eyes, modification of leaf and blood type among others.