The enactment of the Clean Air Act of 1970 (1970 CAA) resulted in a major shift in the federal government's role in air pollution control. This legislation authorized the development of comprehensive federal and state regulations to limit emissions from both stationary (industrial) sources and mobile sources.
Answer:
A) the edict of Milan: making Christianity the state religion
Explanation:
Made christianity as the main religion and also moved capital to Constantinople. He is like a really big turning point for Christianity spread.
I'm not sure this is the answer you're looking for but anyways...
Curtail - to make less by or as if by cutting off or away some part
