Final answer:
Natural selection is not a source of genetic variation; it is a process that shapes how traits are passed on within a population. Genetic variation arises from mutations, sexual reproduction, and sometimes during mitosis if DNA replication errors occur.
Step-by-step explanation:
The question 'Which of the following is not a source of genetic variation?' relates to how genetic diversity is created within populations. Among the choices provided, mutuations, sexual reproduction, and mitosis can all lead to genetic variation. However, natural selection is not a source of genetic variation, but rather a process by which certain heritable traits become more or less common in a population as a result of the reproductive success of organisms interacting with their environment.
Mutations are permanent changes in the DNA sequence that can lead to new genetic variation; sexual reproduction combines the genetic information from two parents to produce offspring with unique combinations of genes; and mitosis, while generally producing identical cells, can also lead to variation if mutations occur during DNA replication.In the context of genetic variation, the correct option that is not a source of genetic variation is D) Mitosis. Mitosis is a cell division process that produces two identical daughter cells with the same genetic information as the parent cell. It does not introduce new genetic variation or alleles into a population.