Proponents of international regulation of environmental issues have always struggled against scientific uncertainty and economic hostility, two obstacles which, from a political standpoint, often have been closely related, as economic hostility toward environmental regulation for economic reasons have (i)____________ the considerable scientific uncertainty underlying most environmental challenges to (ii)____________ of environmental regulation. A. resolved B. exaggerate the efficacy C. gainsaid D. downplay the legitimacy E. exploited F. question the fallibility