The Advantages of Emissions Permits Over Taxes Is/are That

The advantages of emissions permits over taxes is/are that

A) it increases uncertainty about the quantity of pollution that will be emitted.
B) environmental authorities decide on an emissions ceiling in advance of issuing permits.
C) pollutants can be raised to levels that have adverse effects on health.
D) firms whose marginal cost of reducing emissions are lower than the market price of permits will find it more profitable to buy additional permits than to reduce their emissions.