Final answer:
The EPA carries out its responsibilities by regulating greenhouse gases within the framework of existing legislation.
Step-by-step explanation:
The Environmental Protection Agency (EPA) carries out its responsibilities by regulating greenhouse gases within the framework of existing legislation. This means that the EPA can set rules and guidelines to limit greenhouse gas emissions, but it must do so within the boundaries of laws that have been passed by Congress. For example, the EPA can propose regulations for power plants that emit greenhouse gases, but it cannot close power plants as a direct result of these regulations.