Why is it so important for us to decrease our use of fossil fuels?

A. The combustion of fossil fuels are causing a hole in the Ozone layer
B. The combustion of fossil fuels leads to an increase in atmospheric CO2 which leads to global climate change
C. The combustion of fossil fuels help us meet our energy demands, so it is not that important that we switch to alternatives.
D. Fossil Fuels do not harm the environment, but we are running out of them so we need alternatives.

help me please please​