Answer:
The two animals belong to different species.
Step-by-step explanation:
The two animals presented in the question above were subjected to a cross that generated infertile offspring, even though the crossing was done several times all the offspring were infertile. This happens when the two animals belong to different species, causing the union of genetic material between them to generate an infertile offspring that is called a Hybrid.
There are cases of fertile hybrids, but this is extremely rare. In addition, hybrids are not classified into their parents' species, as they generate another species.