Why are people concerned about the sustainability of fossil fuels? explain

People are concerned because humans are pretty dependant on fossil fuels! Did you know 70% of Chinas electricity is Generated from Coal? Thats how dependant we are on Fossil fuels in just one short example,however Fossil fuels aren't bad they are great energy sources! :D Hope that helped ~Feel Free to mark brainliest~

d. stage 4

explanation:

the existence of some kind of demographic transition is widely accepted in the social sciences because of the well-established historical correlation linking dropping fertility to social and economic development.[1] scholars debate whether industrialization and higher incomes lead to lower population, or whether lower populations lead to industrialization and higher incomes. scholars also debate to what extent various proposed and sometimes inter-related factors such as higher per capita income,lower mortality, old-age security, and rise of demand for human capital are involved.[2]

answer; i believe the answer is (25%)plz check first good luck;