Answer:
There's four stages in the classical demographic transition model:
Stage 1 - Pre-transition
In this stage, the birth rates are very high, but also the life expectancy is very low, thus the growth of the population is slow.
Stage 2 - Early transition
In this stage, the birth rates are very high, but the life expectancy is increased, so the population grows rapidly.
Stage 3 - Late transition
In this stage, the birth rates decline slightly, and the life expectancy is a bit higher, thus the population growth is slowing down.
Stage 4 - Post-transition
In this stage, the birth rates are declined significantly, the life expectancy is pretty high, so the population is either growing very slowly, or it is declining.
This guy got me 100% props to him!