Answer:
The behavior of chromosomes during meiosis and fertilization is responsible for most of the variation that arises in each generation. Three mechanisms contribute to genetic variation arising from sexual reproduction: independent assortment of chromosomes, crossing over, and random fertilization.
D is the answer to the question
During metaphase 1, the spindle fibers attach to the centromeres of each chromosome. Both kinetochores of each sister chromatid pair are turned toward the same pole. And 2 members of each chromosome pair (sister chromatids) are pulled into each new cell during anaphase 1.
I think the answer you want is they are called chromatids.
