volcanic emissions combustion of fossil fuels destruction of tropical forests mining and mineral extraction
I gave my students this multiple choice question: Gaseous sulfur dioxide is a compound that combines with water in the atmosphere to form acid rain. What is the primary source of sulfur dioxide?

Only one answer is correct among these 4 choices:
- volcanic emissions
- combustion of fossil fuels
- destruction of tropical forests
- mining and mineral extraction

Could you tell me which one is correct?

combustion of fossil fuels