What is NOT true about the Emission Trading Scheme (ETS)?

Select one:

a. ETS is a levy paid based on the amount of emissions of greenhouse gases (GHGs)

b. ETS are designed to control emissions by allowing participants to trade excess emissions permits.

c. Emissions trading is a market-based scheme for environmental improvement that allows parties to buy and sell permits for emissions or credits for reductions in emissions of certain pollutants.

d. Participants that emit pollutants must obtain sufficient tradeable units to compensate for their emissions.