atmosphere biosphere hydrosphere lithosphere
I gave my students this multiple choice question: Removing the coal from Earth's crust can change the structure of the crust, release methane gas, and contaminate groundwater with heavy metals. Which of Earth's subsystems is most likely to be affected by all these consequences?

Only one answer is correct among these 4 choices:
- atmosphere
- biosphere
- hydrosphere
- lithosphere

Could you tell me which one is correct?

biosphere