What forces are responsible for distributing genetic variation?

The correct option encompasses all the main forces that contribute to the distribution of genetic variation within and among populations.

Natural selection is a process by which certain traits become more common in a population due to the better reproductive success of individuals with advantageous characteristics. It influences genetic variation by favoring alleles that provide some benefits in terms of survival and reproduction.

Genetic drift refers to random changes in allele frequencies in a population, which can result from chance events that disproportionately affect certain individuals. This randomness can lead to the loss or fixation of alleles, altering genetic variation over time, especially in small populations.

Gene flow, also known as gene migration, involves the transfer of genetic material between populations through the movement of individuals or gametes. This process can introduce new alleles to a population, thereby increasing genetic diversity and counteracting the effects of genetic drift.

Together, these three mechanisms—natural selection, genetic drift, and gene flow—interact to shape the genetic structure of populations and contribute to the overall genetic variation observed within species. The integration of these processes highlights the complex nature of evolutionary dynamics and the importance of considering multiple factors when studying genetic variation.