Answer:
The correct answer is option D, that is, bottleneck effect.
Step-by-step 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.