Genetic variation is based on the?

Genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).

Explanation: Random mutations are the ultimate source of genetic variation ... Crossing over (genetic recombination) and random segregation during meiosis can result in the production of new alleles or new combinations of alleles.