The level of sulfur dioxide in the atmosphere is slightly higher than it was ten years ago. This increase is troubling because ten years ago the Interior Ministry imposed new, stricter regulations on emissions from coal-burning power plants. If these regulations had been followed, then the level of sulfur dioxide in the atmosphere would have decreased. Which one of the following can be properly inferred from the statements above? ['If current regulations on emissions from coal-burning power plants are not followed from now on, then the level of sulfur dioxide in the atmosphere will continue to increase.', 'There have been violations of the regulations on emissions from coal-burning power plants that were imposed ten years ago.', 'Government regulations will never reduce the level of sulfur dioxide in the atmosphere.', 'Emissions from coal-burning power plants are one of the main sources of air pollution.']