Answer:
The black dogs are h o m ozygous with a dominant trait, but the brown dogs are h o m ozygous with a recessive trair. So if the dogs breed their offspring will all be black because black is dominant to brown, so therefore black is expressed.
Diagram is in the pic above
Blue box is black dog
Red box is brown dog
A is the allele for black
b is the allele for brown
A is dominant so b, so A is expressed
