The correct option is A Two different related species
Mating of more closely related individuals within the same breed for 4-6 generations is called inbreeding.Practice of mating of animals within the same breed without having common ancestors is called out-crossing. In inter-specific hybridization male and female animals of two different related species are mated.Mating of superior males and females of different breed results in cross-breeding. So the correct option is "two different related species"