Health, population, and environment are interrelated in many ways.
If we are observing one individual person and the health of that person we can see that the health of this individual is associated with the environment where that person is living. Rapid population growth is provoking massive environmental degradation because where there are much people, the environment can face great degradation.
First, decide where you stand on the issue. Sould PE be optional? Then just google reson why it should or shouldnt be and include that in your answer. Hope this helps!