Final answer:
Congress addressed acid rain by amending the Clean Air Act in 1990, introducing a marketable permits system to cut sulfur dioxide emissions and reduce them to half of their 1980 levels.
Step-by-step explanation:
The compromise worked out by Congress to deal with acid rain included amendments to the Clean Air Act in 1990. These amendments aimed to reduce sulfur dioxide emissions from electric power plants by introducing a system of marketable permits and required the plants to reduce emissions to half of their 1980 levels. This legislative action was a pivotal move in addressing environmental issues related to acid rain, which had significant impacts on forests, water bodies, and buildings.