Biology

The correct answer is: A.Bottleneck effect.

Explanation:

The bottleneck effect explains this phenomenon. When the Northern elephant seals were hunted down to a population size of only about 20 individuals in the 1890s, their genetic diversity was drastically reduced. Even though the population has since rebounded to over 30,000 individuals, the genetic diversity remains low because the genetic variation of the original small population was severely limited. The genetic material of the surviving individuals was the only source for the new population, meaning many alleles were lost during the bottleneck event.

B.Adaptation: ...