My question is

In fruit flies, the B and H genes are on chromosome 2, and the G gene is on a chromosome 3. The b mutant allele causes flies to be black. The h mutant allele causes flies to be hairy. The g mutant allele causes flies to be giant sized. For all 3 genes, the mutant allele is recessive to the wild type allele. From mating a pure-breeding black giant female to a pure breeding hairy male. write the genotype and phenotype of the f1

the answer is bH/ Bh; G/g

I’m having a hard time figuring out what the genotype of the parents are

would the female be bb/HH; G/G

and the male BB/hh;g/g

why doesn’t it give Bb/Hh;G/g as an answer?