What observation is explained by the law of independent assortment?

What observation is explained by the law of independent assortment?

a. Recessive trait forms are always hidden in the F 1 generation.
b. Each pair of chromosomes separates on its own during meiosis.
c. Dominant trait forms are always displayed in the F 1 generation.
d. Homologous chromosomes cluster in tetrads during meiosis.