Which of the following explains how the processes involved in meiosis increase variation in a species? A. The gametes of asexually-reproducing organisms automatically reshuffle during meiosis, creating genetic variation in their offspring. B. The gametes of asexually-reproducing organisms undergoing meiosis always contain mutations, creating genetic variation in their offspring. C. The gametes of sexually-reproducing organisms always mutate during meiosis, creating genetic variation in their offspring. D. The gametes of sexually-reproducing organisms reshuffle through crossing over and independent assortment during meiosis, creating genetic variation in their offspring.