Use the following information when answering the corresponding question. Two populations of birds with somewhat different coloration live on two different islands. When birds from the two populations are brought together, they produce young whose appearance is intermediate between the two parents. These offspring can successfully breed with each other or with birds from either parent population, and all offspring of these pairings appear intermediate to various degrees. According to the biological species concept, the two populations on different islands are

A. Different species, under the morphological species concept.
B. Different species, under the biological species concept.
C. Different species, under the phylogenetic species concept.

The species has been classified according to their morphology, habitat and reproduction criteria. The most accepted species concept is Biological species concept.

The population of birds have different coloration and their offspring produce the parents are intermediate colors. Here, the species of birds has been categorized under the morphological species concept.

Thus, the correct answer is option (A).