Choices: i. Pesticides ii. fossil fuels iii. remains of prehistoric life iv. chlorofluorocarbons v. energy of moving objects vi. an erupting volcano vii. harmful substances viii. forest is destroyed
Given those answer options, answer the question: Fact 1: The emission of sulfur dioxide causes acid rain. Fact 2: An erupting volcano emits sulfur dioxide. Given the two facts above, what causes acid rain?
A:
vi.