The description that best explains Mendel's law of independent assortment is:
The arrangement of each pair of homologous chromosomes on the metaphase plate during metaphase I is random with respect to the arrangements of other pairs.
This statement reflects the principle that the orientation of each pair of homologous chromosomes is independent of the orientation of other pairs. As a result, the different combinations of chromosomes can lead to a variety of allele combinations in the gametes, demonstrating the independent assortment of alleles for different genes during meiosis.