Question

What must be true for two organisms to be considered the same species?

Answer 1

 C.  They can produce fertile offspring.

Answer 2

Hello!

Generally, what is considered must be true for two organisms to be considered the same species, is they have to be able to breed and produce offspring between each other.

If a species becomes separated, and over time cannot produce offspring with the other separated group, they are not the same species anymore.

Therefore, your answer is: They must be able to reproduce and produce offspring.

Hope this helped!