Final answer:
Genetic drift is a chance factor that can affect which traits are passed on to future generations in a population, often through random events. Mutations and gene flow also introduce new genetic variation, but it is the genetic drift that operates purely by chance and can lead to significant changes in allele frequencies over time.
Step-by-step explanation:
In any given population, a chance factor that might be passed to future generations is genetic drift. Genetic drift stems from chance events such as natural disasters or accidental deaths, which can lead to certain alleles becoming more or less common simply by chance, not because they are more or less advantageous. In contrast, new genetic variation can be introduced into a population through both mutations, which occur when there are changes in the DNA sequence, and gene flow, which happens when individuals join a population, bringing new alleles with them. While natural selection systematically favors beneficial traits, and mutations can be random, it is the genetic drift that is entirely subject to chance and can lead to significant changes in allele frequencies within a population over time. This can result in a loss of genetic variation and can ultimately impact the population's ability to adapt to changes in the environment. Therefore, genetic drift and mutations are the factors that most readily introduce new genetic materials to a population's genetic composition.