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