What is the most effective approach the government can take to keep the air clean? create and enforce regulations that limit fossil fuel burning by industries use funds to understand why smoke and mold are causes of outdoor air pollutants educate people about the threats to outdoor clean air from visible forms of air pollution modify regulations under the clean air act by including expensive options to reduce air pollution

create and enforce regulations that limit fossil fuel burning by industries  is most likely your correct answer, as two of the four options listed do not help keep air clean for obvious reasons (choice 2 and 3). choice 4 might help but the keyword expensive.

create and enforce regulations that limit fossil fuel burning by industries

answer is  

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to prove that the triangles are congruent using the aas congruence

answercharacteristics of place include things like economic activity, architecture,and culture,all of which are human elements that alter or can be influenced by the environment;