The Following Question Refers to the Essential Steps in Meiosis

The following question refers to the essential steps in meiosis described below.
1. Formation of four new nuclei, each with half the chromosomes present in the parental nucleus
2. Alignment of tetrads at the metaphase plate
3. Separation of sister chromatids
4. Separation of the homologs; no uncoupling of the centromere
5. Synapsis; chromosomes moving to the middle of the cell in pairs
-How does the sexual life cycle increase the genetic variation in a species?

A) by allowing crossing over
B) by allowing fertilization
C) by increasing gene stability
D) by conserving chromosomal gene order
E) by decreasing mutation frequency