Several billion years ago, which gas was the least prevalent in the atmosphere

all fossil fuels are nonrenewable, so think coal, gasoline, things that we will eventually run out of. all fossil fuels are nonrenewable resources, but not all nonrenewable recourses are fossil fuels. these resources are not being renewed as fast as we are using them. i hope this considering there weren't any answer choices.

i'm sure the answer you are looking for would be

a. an ice age

hope this contact me if this didn't or you need with more answers : )