Question

horses and zebras can be bred to produce a zorse, which is infertile. which is most likely the reason zebras and horses are considered separate species?
they cannot breed.
their offspring cannot breed.
they look different from each other.
they are found in different habitats.

Explanation:

According to the biological species concept, a species is a group of organisms that can interbreed and produce fertile offspring. Horses and zebras can breed, but their offspring (zorses) are infertile. This reproductive isolation (specifically hybrid infertility) is a key factor in classifying them as separate species. The fact that their offspring cannot breed (are infertile) is the most relevant reason here. The option "They cannot breed" is incorrect as the problem states they can breed. "They look different" and "found in different habitats" are not the most definitive biological reasons for species separation compared to reproductive isolation (hybrid infertility).

Answer:

Their offspring cannot breed.