Asubstance that enters earth's cycles and does harm to living things is

“obamacare”: included a provision for government-run health insurance called “the public option.” was bitterly opposed by congressional republicans because most favored a “single-payer” plan. survived two challenges to its constitutionality. was partially repealed in 2013 in order to avert a government shutdown. led to the expansion of medicaid in republican controlled states.