Final answer:
Independent assortment is based on gametes getting only one copy of each allele of each gene.
Step-by-step explanation:
The correct answer is A. Independent assortment. Independent assortment is based on gametes getting only one copy of each allele of each gene. During gamete formation, the alleles for each gene segregate from each other so that each gamete carries only one allele for each gene. This process allows for the random distribution of traits in offspring and increases genetic diversity.