Assume the Price of a Tradable Emissions Permit for a Ton

Assume the price of a tradable emissions permit for a ton of sulfur dioxide is $150.Which of the following is incorrect?

A) A firm that buys permits has an incentive to limit pollution up to the point at which the marginal benefit of emissions is equal to $150.
B) A firm that has more permits than it plans to use has an incentive to limit pollution up to the point at which the marginal benefit of emissions is equal to $150.
C) The opportunity cost of emitting a ton of sulfur dioxide is $75 for all firms.
D) The opportunity cost of emitting a ton of sulfur dioxide is $150 for all firms.