Answer: A. genetic drift
Genetic drift is a mechanism of evolution. Random irregularities and fluctuations in allele frequency from one generation to another generation as a result of chanced events describe the entire concept of Genetic drift. Genetic drifts can cause traits to be dominant or disappear from a population. Its effects are most pronounced in small populations. Genetic drift is more like the shuffling of our DNA frequency from one generation to another. With this, some genes become dominant and others are lost. Once it begins, genetic drift will continue until either the allele becomes entirely dominant, or is completely lost by a population.