Cross between AaBB and aaBB will form:

Explanation

The correct option is a) 1 AaBB : 1 aaBB. Let's explain why the other options are incorrect: b) All AaBB: This option suggests that all offspring will have the AaBB genotype. However, this is not possible because the cross involves one parent with the genotype AaBB and the other parent with the genotype aaBB. Since both parents contribute one allele for each gene, the offspring will inherit one allele from each parent for each gene. Therefore, the expected outcome will include a combination of AaBB and aaBB genotypes. c) 3 AaBB : 1 aaBB: This option suggests a ratio of 3 AaBB to 1 aaBB offspring. However, in the given cross, the genotypes of both parents involve one parent with the genotype AaBB and the other parent with the genotype aaBB. Each parent can contribute either the AaBB or aaBB genotype to their offspring. Therefore, the expected outcome will be a 1:1 ratio of AaBB to aaBB genotypes. d) 1 AaBB : 3 aaBB: This option suggests a ratio of 1 AaBB to 3 aaBB offspring. Again, this ratio is not possible with the given cross involving one parent with the genotype AaBB and the other parent with the genotype aaBB. Each parent can contribute either the AaBB or aaBB genotype to their offspring. Therefore, the expected outcome will be a 1:1 ratio of AaBB to aaBB genotypes. In summary, the correct option is a) 1 AaBB : 1 aaBB because the cross between AaBB and aaBB parents will result in a 1:1 ratio of offspring with the AaBB and aaBB genotypes.