Unsupported. The level of sulfur dioxide increased because the regulations were not followed, but we don’t know what might happen if the regulations are not followed from now. Sulfur dioxide might continue to increase, or it might level out, or something else might reduce it.

Very strongly supported. If the regulations had been followed, the level of sulfur dioxide in the atmosphere would have decreased. But the level of sulfur dioxide has increased, so the regulations must not have been fully followed.

Unsupported. The stimulus doesn’t tell us anything about what might happen if regulations are made stronger. We only know that if the original regulations had been followed, then sulfur dioxide levels would have decreased.

Unsupported. Power point emissions caused an increase in the level of sulfur dioxide in the atmosphere, but we don’t know that they’re one of the main sources of air pollution.

Unsupported. The regulations imposed ten years ago didn’t successfully reduce the level of sulfur dioxide in the atmosphere, but that doesn’t mean that government regulations will never reduce it.