I NEED HELP NOWWW.! Sexual reproduction influences genetic variation. Which of the following properly describes the influence that sexual reproduction has on genetic variation?

A) Crossing over occurs during meiosis, which results in the exchange of alleles between homologous chromosomes. This exchange of genetic material allows for the production of new combinations of alleles in gametes and an increase in genetic variation.

B) Crossing over occurs during mitosis, which results in the exchange of alleles between homologous chromosomes. This exchange of genetic material allows for the production of new combinations of alleles in gametes and an increase in genetic variation.

C) Crossing over occurs during mitosis, which results in the exchange of alleles between sister chromatid. This exchange of genetic material allows for the production of identical combinations of alleles in gametes and a decrease in genetic variation.

D) Crossing over occurs during meiosis, which results in the exchange of alleles between sister chromatid. This exchange of genetic material allows for the production of identical combinations of alleles in gametes and a decrease in genetic variation.