Many air pollutants, including NO_X, are produced by electric power plants and manufacturing plants that burn fossil fuels. To reduce total NO_X emissions in a region the regulatory agency decides to use a tax on emissions. Engineers tell them it is less expensive to reduce NO_X from electric plants than from other manufacturing facilities. Because of this cost difference, the regulators propose to set a low tax rate for NO_X emissions from all power plants and a high tax rate for NO_X emissions from all manufacturing plants. As an economist, what is good or bad about this plan? Include a graph in your answer.