Final answer:
Mendel's Law of Independent Assortment, which is a fundamental principle in genetics, states that alleles of different genes assort independently into gametes. This results in a variety of genetic combinations among the offspring when two traits are considered, as demonstrated by Mendel's dihybrid crosses in pea plants.
Step-by-step explanation:
The law that describes when alleles of unlinked genes assort independently is Mendel's Law of Independent Assortment. This law is essential in understanding genetic variation and inheritance patterns. It suggests that the alleles for different genes segregate into gametes independently of one another. This is best illustrated through dihybrid crosses, a type of cross Mendel used to confirm this law by examining two different traits at the same time, like seed color and seed texture in pea plants. For example, in a cross between a pea plant with green, wrinkled seeds (rryy) and one with yellow, round seeds (RRYY), independent assortment predicts that the resulting F1 generation will have all possible combinations of alleles, specifically those with genotype RrYy.