An inter-breeding population of finches became separated geographically, forming two isolated groups. Each group then became subect to different selective pressures. One group was then introduced into the habitat of the other.
Which one of the following would determiner wheather they now formed two district species?

Options

A. They had been separated for more than three milion years.
B. They failed to produce fertile `F_(1)` hybrids.
C. They showed marked differences in the shape of their beaks.
D. Their plumage had become markely different.

Answer

B

Explanation

Once inter-breeding population of finches, now have failed to produce fertile `F_(1)` hybrids, this means they have now formed tow distinct species.