Answer:
B. many members of a population die, resulting in a great loss of genetic diversity
Step-by-step explanation:
When certain environmental fluctuations such as reduced food supply or an outbreak of disease result in a sudden decrease in the population size, the population is said to be going through a bottleneck. Bottleneck reduces genetic diversity due to the loss of alleles/genes from the population. Therefore, the death of many members of a population due to some adverse environmental factors and the resultant reduction in genetic diversity represents the bottleneck effect.