Final answer:
Genetic reassortment during meiosis is contributed by a) independent assortment and crossing-over. These processes lead to the formation of genetically diverse gametes.
Step-by-step explanation:
Genetic reassortment occurs during meiosis through two main processes: independent assortment and crossing-over. Independent assortment refers to the random alignment of homologous chromosomes on the metaphase plate during meiosis I, resulting in the creation of gametes with a mixture of maternal and paternal chromosomes.
Crossing-over, on the other hand, involves the exchange of genetic material between homologous chromosomes during prophase I of meiosis I. This exchange leads to the formation of recombinant chromosomes and increases genetic variation in offspring. Therefore, options a, b, and d contribute to genetic reassortment during meiosis.