The northern elephant seal was hunted almost to extinction during the 18th and 19th centuries. Less than 100 seals were left to contribute to the gene pool of their future generations. Since the early 20th century, the elephant seals have been protected by law in both the U. S. and Mexico. Over 100,000 seals now inhabit the western shores of North America, all related to the small population that survived the slaughter of hunters. Scientists fear the elephant seals may be more susceptible to disease and pollution due to a .A. heterozygous advantageB. disruptive type of selectionC. Founder EffectD. Bottleneck Effect

The correct answer is option D, that is, bottleneck effect.

Explanation:

A phenomenon, which occurs due to events like earthquakes, floods, or other natural calamities that result in the severe declination in the size of a particular population is known as the bottleneck effect. The bottleneck effect is an extreme illustration of genetic drift that results in the reduction of a population's genetic variability.  

With the decline in the size of a specific population, a reduction in the genetic variability of the same population is witnessed due to the loss of alleles. This eventually makes the population vulnerable to pollution and diseases. Hence, the given case is an example of the bottleneck effect.