Economists generally favor the use of tradable emissions allowances to reduce pollution. However, the use of these allowances has been criticized by some environmentalists. Which of the following describes this criticism?

Some environmentalists oppose allowances on legal grounds; they believe the use of allowances is unconstitutional.
Some environmentalists believe that the price of allowances is often too high for consumers to afford.
Some environmentalists believe the allowances give firms a license to pollute.
Some environmentalists believe that Pigovian taxes are a more efficient way to reduce pollution.