Answer:
This is possible by mating the domestic dog with the gray wolf. Explanation is given below.
Step-by-step explanation:
A Species can be defined as a group of individuals which are capable of producing fertile offspring by undergoing sexual interaction with each other, that is, they are capable of inter-breeding.
In order determine whether domestic dog and gray wolf belong to the same species, male and female individual from each of the group are interbred with each other.
If the mating gives rise to fertile offspring, then domestic dog and gray wolf would belong to the same species.
If no fertile offspring is generated by the mating then the domestic dog and the gray wolf belong to two different species.
This is because Reproductive Isolation prevents inter-species breeding.