Answer:
The answer is A. The establishment of a small colony of nonhuman primates on an isolated island.
Explanation:
The founder effect refers to the effect that a small initial number of settling individuals has on the genetic variability of that initial population, which loses much of their original variability due to the many genes that are absent from those few initial settlers. As they reproduce and the population grows it becomes distinct from the source population in the mainland and may lead to a new variety or even a new species given enough time.