Answer
Dogs have many coat colors, for example let us take B series here black will be denoted by B and brown by b.
When we cross them Bb will be formed, this is black color with heterozygous genotype. In F2 generation it will produce BB, Bb, and bb, in 1:2:1 ratio
F2 Generation:
| B | b | |
| B | BB | Bb |
| b | Bb | bb |