The correct answer is A. Two populations of finches that cannot produce viable offspring
Explanation:
Reproductive isolation is a biological and evolutionary phenomenon that prevents two species from successfully reproducing, this means they cannot produce offspring or the offspring is not fertile, even if these species had a common ancestor. Additionally, as a result of reproductive isolation, each species keeps its genes and features. This phenomenon is best exemplified in "Two populations of finches that cannot produce viable offspring " because this refer to the barriers for different species to reproduce or produce viable offspring, which is the focus of reproductive isolation.
