The correct answer is mitosis. All organisms undergo DNA replication for reproduction, growth, repair, etc. DNA replication occurs before the process of the cell division or commonly known as mitosis. Mitosis is the process in which the cell is being divided into two and replicate DNA to the other to produce a whole new cell.
A is the final correct answer
Those changes in an individuals' genotype that ensure genetic variation begin to be done in Metaphase, where chromosomes are aligned to the equatorial axis of the cell, and eventually, each chromosome is pulled to each pole of the cell during Anaphase I. After this process, follows telophase I, where we can say that each chromosome is given to each of the two daughter cells. We can say then that the creation of different versions of alleles begins with Telophase I.