Meiosis, which occurs during sexual reproduction, allows for a great variety of possible gene combinations. which of the following can increase genetic variation during meiosis? a. the deletion of a gene caused by an error in chromosomal crossover b. the transposition of a gene from one place in an organism's genome to another c. the exchange of genes during chromosomal crossover d. the duplication of a gene caused by an error in chromosomal crossover