D) is the correct option
Explanation:
Northern elephant seal is an example of bottleneck effect
In bottleneck effect the elimination of inferior genotype from a homogeneous gene pool occurs due to the strong natural selection pressure and changing environmental conditions which leads to the genetic drift and only a few most adapted genotype survives and flourish
In case of Northern elephant seal, due to hunting a population decline occurred, environmental conditions changed as a result few genotypes homozygous for every gene is present