Answer:
Great interdependence.
Explanation:
There is a great interdependence between healthy population and its environment because the environment has direct effect on health of people that lives in it. If the environment has pollution so it can causes different diseases and infections in the body of people that lives and expose to that environment while on the other hand, if the environment is clean so it causes good effect on the individuals.
Gangrene is definitely not a common symptom.
I am pretty sure the answer is letter C
None really unless you are talking about an animal
