A change in the frequency of alleles that occurs by chance is called:

Explanation

The question describes the definition of a genetic drift, which is a change in the frequency of alleles that occurs purely by chance. A mutation (option B) describes a change in DNA sequence. Migration (option C) describes the influx or the efflux of individuals into or out of a population, respectively. Natural selection (D) can be confused with genetic drift as both are mechanisms for evolution, but the main difference lies in the fact that in natural selection, allele frequencies change over time not by chance, but due to certain alleles conferring a selective advantage to some individuals over the other (hence, it is not driven by chance, but driven by factors that are useful to the individual and ensures their survival).