Answer:
convergent evolution
Step-by-step explanation:
Convergent evolution is a process of evolutionary change that occurs when two different species, which are unrelated or do not share a common ancestral origin, evolve similar structures independently to become well adapted to their environments which are similar or have the same environmental conditions prevalent in them.
Convergent evolution is the opposite of divergent evolution. Organisms with different ancestral origin develop similar features and structures independently as a result of adaptation to similar environmental conditions. These structures are said to be analogous structures.
Examples of convergent evolution can be seen in hummingbird and the hummingbird moth, the streamline body shape of dolphins, etc.
Therefore, the most likely reason that species A and species B, that are unrelated, share similar trait but live in distinct environments that are similar is convergent evolution.