Please help me with genetics question

Question

In Labrador retrievers, coat color is controlled by two genes. One gene determines black (B_) or brown (bb) hair. However, if the second gene is homozygous recessive (ee), the coat color is yellow. A brown dog was mated to a yellow dog and they produced 4 black and 3 brown puppies. What were the genotypes of the brown and yellow parents, respectively?

Question 10 options:

	BbEe X bbee
	bbEE X BBee
	bbEe X Bbee
	BbEe X BbEe
	bbEE X Bbee

Answer 1

Based only on the given coloring of the parents, we know the yellow dog is __ee and the brown dog is bbE_. These dogs produced four black pups (B_E_) and three brown pups (bb_E_).

We know that as the offspring had a B allele as evident from the black pups, which could have only come from the yellow parent which we now can say is B_ee. The yellow parent produced brown pups with the brown parent, indicating that the yellow parent cannot be homozygous for the black allele (BB) because then all the pups would be black (Bb), so we can now say that the yellow parent's genotype is Bbee.

This eliminates answers 1) BbEe X bbee, 2) bbEE X BBee, and 4) BbEe X BbEe. We are left with either 3) bbEe X Bbee or 5) bbEE X Bbee. It is possible for the brown dog to be either bbEe or bbEE and produce the offspring told to us in the question, however it is most likely that the brown parent is bbEE because of the seven offspring all received a E allele from this parent as evident by now of the offspring being yellow (ee). Therefore, the brown dog's genotype is bbEE and the yellow dog's genotype is Bbee.