Which process increases genetic variation within a population?

The process that increases genetic variation within a population is mutation. Mutations are changes in the DNA sequence of an organism's genome and can occur due to various environmental factors or errors in DNA replication. These changes can introduce new alleles, or variations of genes, into a population, thereby increasing its genetic diversity.

This genetic variation is crucial for the process of evolution, as it provides the raw material on which natural selection can act. Without mutations, populations would become genetically uniform over time, reducing their ability to adapt to changing environments and increasing the risk of extinction.

In contrast, natural selection acts on existing genetic variation, favoring certain traits over others but not necessarily creating new genetic diversity. Extinction eradicates genetic material rather than enhancing it, and stabilizing selection promotes the maintenance of a particular trait, thereby reducing variation rather than increasing it. Thus, mutation is the key process that contributes to genetic variability within a population.