Which of the following is a requirement for successful selective breeding?

Successful selective breeding relies on the presence of genetic variation within the population. This variation provides a pool of different traits from which breeders can select individuals that exhibit desirable characteristics. Without genetic variation, there would be no differing traits to choose from, which would limit the effectiveness of selective breeding.

For instance, if all individuals in a population were genetically identical, any selection for specific traits would be futile because there would be no alternative traits to select for improvement. By having a range of traits to select from, breeders can enhance or introduce beneficial characteristics into the population, leading to improved outcomes, such as increased yields in crops or desirable traits in livestock. Thus, genetic variation is fundamental for the success of selective breeding.