Answer:
The evidence that indicates that horses and donkeys are not the same species is:
D. The mule that results from this mating, is sterile and not able to produce offspring of its own.
Step-by-step explanation:
Mules are result of the mating between a male donkey and a female horse (a mare). Donkeys have 62 chromosomes, and horses have 64. Mules have a mixture of that - 63 chromosomes. That is what prevents the chromosomes from pairing up. As a consequence, mules end up not being able to create embryos properly, which makes them sterile.