Observe given figure and identify example which exhibit given phenomena?

A population bottleneck is a sharp reduction in the size of a population due to environmental events (such as earthquakes, floods, fires, disease, or droughts) or human activities (such as genocide). Such events can reduce the variation in the gene pool of a population. After an event, a smaller population, with a correspondingly smaller genetic diversity, remains to pass on genes to future generations of offspring. A classic example of a population bottleneck is that of the northern elephant seal, whose population fell to about 30 in the 1890s. Although it now numbers in the hundreds of thousands, the potential for bottlenecks within colonies remains. Genetic bottlenecks exist in cheetahs. Hypochodriac people are not an example of bottle neck effect. Thus, option D is correct.