Which type of cell division is responsible for variability among members of a species, mitosis or meiosis? Why?
It is meiosis. During this process, crossing over and random assortment of homologous chromosomes contribute to new genetic combinations, which is a measure of variability. Then, random fusion between haploid gametes further contributes to new combinations.
Mitosis does not result in new combinations, as the daughter cells are identical to each other and the parental cell.