Answer: b
An inherited modification of structure or function that allows an organism to survive and reproduce in its environment.
Step-by-step explanation:
Adaptation helps an organism to become better suited to survive and reproduce in its environment. It is change in an organism's structure or behavior.
Change in physical features of an organism is considered as structural adaptation. Example- fur in bear
Change in the way an organism does things to survive is called behavioral adaptation. Example- bird calls and migration from one place to another.
Adaptation is an essential feature that helps an organism to better servive in the environment. In case, an organism fails to adapt to changes in its environment, its immune system becomes weak and fails to work. This threatens its life and it becomes ill. This may also result in its death.