2. reaction 3. body functions
The process of natural selection is a part of the evolution process. Let's take a herd of animals that live together so as to defend themselves and survive. If animals from the herd don't live by herd rules or similar, they will get eaten by predators or die. In time, the rebellious animals will die out leaving only those that live as a herd, and this trait will be transferred to their off-springs who will in turn behave as the herd too.
I believe it is b the definition for histopathology is the study in changes in tissue caused by disease
