How does total population change from Stage 1 to Stage 4?

The total population increases.

Explanation:

Stage 1 has high birth and death rates, as well as short life expectancy.  Stage 4 has low birth and death rates, and a high dependency ratio and long life expectancy.  Changes in medical care are a major reason for these changes.  

When looking at a Demographic Transition model, you can see the line for total population rising from Stage 1 to Stage 4, meaning it's increasing.  

lol i would say c -porductivity

i think it's severe storms but i might be wrong