The correct option is D Reduced fertility and productivity due to continued close inbreeding
Inbreeding is the mating of closely related animals (having common ancestors) within the same breed for 4 to 6 generations.
In inbreeding, the progeny obtained are evaluated in every generation and the superior male and females are selected for further mating. Thus, inbreeding helps in the accumulation of superior genes and elimination of less desirable genes.
But it has been observed that continued inbreeding results in reduced fertility and productivity. This is called inbreeding depression.