Answer:
A
Step-by-step explanation:
The correct answer would founder effect.
The founder effect is created when a population suddenly suffers a loss in genetic variability (due to loss of members within it) either due to migration or catastrophe and the remaining members of the population survive to re-establish the population. In order words, found effects occur when just a few members of a population become isolated from the original population and end up forming their own population.
The new population that is formed would only have a small percentage of the genetic variation of the original population.
The founder effect is quite different from the bottleneck effect in that the latter represents a reduction in genetic variability that occur due to a short term reduction in the original population. A reduced genetic variability is created due to the reduction in population and by the time the population is restored, the reduction in genetic variability becomes permanent.
The correct option is, therefore, A.