Associated Press: Power generator Exelon became the latest utility to drop its membership in the U.S. Chamber of Commerce because of the group’s opposition to legislation that would limit emissions of greenhouse gases. “Inaction on climate is not an option,” John Rowe, Exelon’s chairman and chief executive, said in a speech at an energy-efficiency conference. “If Congress does not act, the EPA will, and the result will be more arbitrary, more expensive and more uncertain for investors and the industry …