With independent assortment, the ratio of genotypes in the F2 generation of a cross between true-breeding strains (AA bb x aa BB) can be described as 1:2:1:2:4:2:1:2:1. To what genotype does the "4" in the ratio refer?a. AA Bb
b. Aa BB
c. Aa Bb
d. None of the answer options is correct.