Answer: Use this link to find out the answer to your question - https://populationeducation.org/stage-1-demographic-transition-model/ (If you can't click it then just copy-paste it in a new tab)
They study the physical systems as an example of natural changes that take places like the hurricane, cyclone earthquake, and even floods. These change the earth's surface areas and these are physical changes that are interrelated and interlinked with each other.
