Which example illustrates an environmental policy based on tradable emission permits?

A) a charge to companies of $1 for every 100 units of pollutants emitted
B) paying companies $1 for each 10% reduction in emissions
C) allowing companies to buy and sell the right to a certain level of emissions
D) ignoring pollution and letting private markets operate without government interference

Tradable emission permits allow companies to buy and sell the right to emit a certain level of pollutants. This creates a market-based approach to reducing pollution, as companies that can reduce their emissions below their allotted level can sell their excess permits to those who cannot meet their allotted level. This creates an incentive for companies to reduce their emissions and rewards those who can do so most efficiently.