Question

Dr. Disney has been raising exotic fruit flies for decades. Recently, he discovered a strain of fruit flies that in the recessive condition have baby blue eyes that he designates as bb. He also has another strain of fruit flies that in the recessive condition have pink wings that are designated as pw. He is able to establish flies that are homozygous for both mutant traits.
He mates these two strains with each other. Dr. Disney then takes phenotypically wild- type females from this cross and mates them with double recessive males. In the resulting testcross progeny, he observes 500 flies that are of the following makeup:

41 with baby blue eyes and pink wings
207 with baby blue eyes only
210 with pink wings only
42 with wild-type phenotype

14. Assuming the wild-type alleles for these two genes are b+ and pw+, what is the correct testcross of the F1 flies?
A) b+ pw+/b pw ⋅ b pw/b pw
B) b+ pw+/b pw ⋅ b pw+/b+ pw
C) b+ pw/b pw+ ⋅ b pw/b pw
D) b+ pw/b pw+ ⋅ b+ pw+/b pw
E) b+ pw+/b pw ⋅ b+ pw/b pw+

The answer is C but I need some help figuring out why. Thanks!

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