In biology, the strain is a low-level taxonomic rank used in different contexts:
In microbiology, a strain is a part of a bacterial species different from other bacteria of the same species by a minor but identifiable difference. Strains are often created in the laboratory by mutagenesis existing strains or wild-type examples of bacterial species.
In zoology, a strain corresponds to an individual or group of individuals who are at the origin of a line of descendants, sometimes called the holotype, paratypes, etc. A strain is a population of organisms that descends from a single organism or pure isolate culture. Strains of the same species may differ slightly from each other in many respects.
A strain thus consists of a group of organisms of the same species possessing certain differential traits based on their relationship; either they come from the same region, as the same watershed of a river, or they are the fruit of a particular breeding program (exists as a whole interbreeding without introductions from external sources).
Answer:
C) genetic drift.
Explanation:
Genetic drift is the random change in the frequency of alleles in a population due to random sampling. Many circumstances can lead to genetic drift for example bottleneck effect, founder effect, etc.
The bottleneck effect occurs when most of the members of a population die because of any natural disaster like flood, fire, etc. This can cause a certain allele to be lost in the remaining population because of losing major populations. So here due to hurricane half of the mammal population gets eliminated which shows it is an example of the genetic drift.