The correct answer is D. White hair of adult polar bears
Step-by-step explanation:
Adaption refers to a natural process that involves a change in behavior or traits in a species or population to make this more suitable to survive. Indeed, adaptations help an organism to survive in a specific environment or adapt to changes. Besides this, adaptation is the result of processes such as natural selection through which more fit organisms survive and pass fitness traits to new generations.
According to this, the one that is an example of adaptation is the "white hair of adult polar bears" because this phenotype (visible trait) helps polar bears to camouflage in the Artic, in this way, polar bears can avoid possible predators and have more chances to hunt. This means, this trait makes polar bears more suitable to survive and due to this, it is an adaptation.